Publications

Last update: Apr 16, 2024

Books

[ 1]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Computational Fluid–Structure Interaction: Methods and Applications”, Wiley (2013), 10.1002/9781118483565
Times Cited in Scopus: 496
@BOOK{Bazilevs13a, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Computational {F}luid–{S}tructure {I}nteraction: {M}ethods and {A}pplications}, YEAR = {January 2013}, PUBLISHER = {Wiley}, DOI = {10.1002/9781118483565}, ISBN = {978-0470978771} } Abstract:
Computational Fluid-Structure Interaction: Methods and Applications takes the reader from the fundamentals of computational fluid and solid mechanics to the state-of-the-art in computational FSI methods, special FSI techniques, and solution of real-world problems. Leading experts in the field present the material using a unique approach that combines advanced methods, special techniques, and challenging applications. This book begins with the differential equations governing the fluid and solid mechanics, coupling conditions at the fluid-solid interface, and the basics of the finite element method. It continues with the ALE and space-time FSI methods, spatial discretization and time integration strategies for the coupled FSI equations, solution techniques for the fully-discretized coupled equations, and advanced FSI and space-time methods. It ends with special FSI techniques targeting cardiovascular FSI, parachute FSI, and wind-turbine aerodynamics and FSI. Key features: First book to address the state-of-the-art in computational FSI Combines the fundamentals of computational fluid and solid mechanics, the state-of-the-art in FSI methods, and special FSI techniques targeting challenging classes of real-world problems Covers modern computational mechanics techniques, including stabilized, variational multiscale, and space-time methods, isogeometric analysis, and advanced FSI coupling methods. Is in full color, with diagrams illustrating the fundamental concepts and advanced methods and with insightful visualization illustrating the complexities of the problems that can be solved with the FSI methods covered in the book. Authors are award winning, leading global experts in computational FSI, who are known for solving some of the most challenging FSI problems. Computational Fluid-Structure Interaction: Methods and Applications is a comprehensive reference for researchers and practicing engineers who would like to advance their existing knowledge on these subjects. It is also an ideal text for graduate and senior-level undergraduate courses in computational fluid mechanics and computational FSI. © 2013 John Wiley & Sons, Ltd.

Edited Volumes

[ 8]

Y. Bazilevs and K. Takizawa, “Advances in Fluid–Structure Interaction”, Computers & Fluids, 141 (2016) Computers & Fluids, Elsevier
@ARTICLE{EditedVolume8, AUTHOR = {Y.~Bazilevs and K.~Takizawa}, TITLE = {{A}dvances in {F}luid–{S}tructure {I}nteraction}, VOLUME = {141}, YEAR = {2016}, BOOKTITLE = {Computers \& Fluids}, ADDRESS = {Amsterdam}, NOTE = {\textit{Computers \& Fluids}, Elsevier} }

[ 7]

Y. Bazilevs and K. Takizawa, “Advances in Computational Fluid–Structure Interaction and Flow Simulation: New Methods and Challenging Computations”, Modeling and Simulation in Science, Engineering and Technology (2016) Springer
@ARTICLE{EditedVolume7, AUTHOR = {Y.~Bazilevs and K.~Takizawa}, TITLE = {{A}dvances in {C}omputational {F}luid–{S}tructure {I}nteraction and {F}low {S}imulation: {N}ew {M}ethods and {C}hallenging {C}omputations}, VOLUME = {None}, NUMBER = {None}, YEAR = {2016}, BOOKTITLE = {Modeling and Simulation in Science, Engineering and Technology}, ADDRESS = {Berlin}, ISBN = {978-3-319-40827-9}, NOTE = {Springer} }

[ 6]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Stabilized and Multiscale Methods in Fluid Dynamics Modeling”, Mathematical Models and Methods in Applied Sciences, 25 (2015) World Scientific
@ARTICLE{EditedVolume6, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {{S}tabilized and {M}ultiscale {M}ethods in {F}luid {D}ynamics {M}odeling}, VOLUME = {25}, NUMBER = {12}, YEAR = {2015}, BOOKTITLE = {{M}athematical {M}odels and {M}ethods in {A}pplied {S}ciences}, ADDRESS = {Berlin}, NOTE = {World Scientific} }

[ 5]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Computational Fluid Mechanics and Fluid–Structure Interaction”, Computational Mechanics, 54 (2014) Computational Mechanics, Springer
@ARTICLE{EditedVolume5, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Computational {F}luid {M}echanics and {F}luid–{S}tructure {I}nteraction}, VOLUME = {54}, NUMBER = {4}, YEAR = {2014}, BOOKTITLE = {Computational Mechanics}, ADDRESS = {Berlin}, NOTE = {\textit{Computational Mechanics}, Springer} }

[ 4]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Computational Fluid–Structure Interaction, Mathematical Models and Methods in Applied Sciences”, Mathematical Models and Methods in Applied Sciences, 23 (2013) World Scientific
@ARTICLE{EditedVolume4, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Computational {F}luid–{S}tructure {I}nteraction, {M}athematical {M}odels and {M}ethods in {A}pplied {S}ciences}, VOLUME = {23}, NUMBER = {2}, YEAR = {2013}, BOOKTITLE = {{M}athematical {M}odels and {M}ethods in {A}pplied {S}ciences}, NOTE = {World Scientific} }

[ 3]

K. Takizawa, Y. Bazilevs, and T.E. Tezduyar, “Computational Fluid Mechanics and Fluid–Structure Interaction”, Computational Mechanics, 50 (2012) Computational Mechanics, Springer
@ARTICLE{EditedVolume3, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar}, TITLE = {Computational {F}luid {M}echanics and {F}luid–{S}tructure {I}nteraction}, VOLUME = {50}, NUMBER = {6}, YEAR = {2012}, BOOKTITLE = {Computational Mechanics}, ADDRESS = {Berlin}, NOTE = {\textit{Computational Mechanics}, Springer} }

[ 2]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Computational Fluid Mechanics and Fluid–Structure Interaction”, Journal of Applied Mechanics, 79 (2012) Journal of Applied Mechanics, ASME
@ARTICLE{EditedVolume2, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Computational {F}luid {M}echanics and {F}luid–{S}tructure {I}nteraction}, VOLUME = {79}, YEAR = {2012}, BOOKTITLE = {Journal of Applied Mechanics}, ADDRESS = {New York}, NOTE = {\textit{Journal of Applied Mechanics}, ASME} }

[ 1]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Computational Fluid Mechanics and Fluid–Structure Interaction”, Computational Mechanics, 48 (2011) Computational Mechanics, Springer
@ARTICLE{EditedVolume1, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Computational {F}luid {M}echanics and {F}luid–{S}tructure {I}nteraction}, VOLUME = {48}, NUMBER = {3}, YEAR = {2011}, BOOKTITLE = {Computational Mechanics}, ADDRESS = {Berlin}, NOTE = {\textit{Computational Mechanics}, Springer} }

Journal Articles Indexed by the Web of Science

[128]

Y. Taniguchi, K. Takizawa, Y. Otoguro, and T.E. Tezduyar, “A hyperelastic extended Kirchhoff–Love shell model with out-of-plane normal stress: II. An isogeometric discretization method for incompressible materials”, Computational Mechanics, published online, doi: 10.1007/s00466-024-02445-9 (2024), 10.1007/s00466-024-02445-9
@UNPUBLISHED{Taniguchi24a, AUTHOR = {Y.~Taniguchi and K.~Takizawa and Y.~Otoguro and T. E.~Tezduyar}, TITLE = {A hyperelastic extended {K}irchhoff–{L}ove shell model with out-of-plane normal stress: {II}. {A}n isogeometric discretization method for incompressible materials}, YEAR = {2024}, DOI = {10.1007/s00466-024-02445-9}, NOTE = {\textit{Computational Mechanics}, published online, doi: 10.1007/s00466-024-02445-9} } Abstract:
This is Part II of a multipart article on a hyperelastic extended Kirchhoff–Love shell model with out-of-plane normal stress. We introduce an isogeometric discretization method for incompressible materials and present test computations. Accounting for the out-of-plane normal stress distribution in the out-of-plane direction affects the accuracy in calculating the deformed-configuration out-of-plane position, and consequently the nonlinear response of the shell. The return is more than what we get from accounting for the out-of-plane deformation mapping. The traction acting on the shell can be specified on the upper and lower surfaces separately. With that, the model is now free from the “midsurface’ location in terms of specifying the traction. In dealing with incompressible materials, we start with an augmented formulation that includes the pressure as a Lagrange multiplier and then eliminate it by using the geometrical representation of the incompressibility constraint. The resulting model is an extended one, in the Kirchhoff–Love category in the degree-of-freedom count, and encompassing all other extensions in the isogeometric subcategory. We include ordered details as a recipe for making the implementation practical. The implementation has two components that will not be obvious but might be critical in boundary integration. The first one is related to the edge-surface moment created by the Kirchhoff–Love assumption. The second one is related to the pressure/traction integrations over all the surfaces of the finite-thickness geometry. The test computations are for dome-shaped inflation of a flat circular shell, rolling of a rectangular plate, pinching of a cylindrical shell, and uniform hydrostatic pressurization of the pinched cylindrical shell. We compute with neo-Hookean and Mooney–Rivlin material models. To understand the effect of the terms added in the extended model, we compare with models that exclude some of those terms.

[127]

E. Wobbes, Y. Bazilevs, T. Kuraishi, Y. Otoguro, K. Takizawa, and T.E. Tezduyar, “Complex-Geometry IGA Mesh Generation: application to structural vibrations”, Computational Mechanics, published online, doi: 10.1007/s00466-023-02432-6 (2024), 10.1007/s00466-023-02432-6
@UNPUBLISHED{Wobbes23b, AUTHOR = {E.~Wobbes and Y.~Bazilevs and T.~Kuraishi and Y.~Otoguro and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Complex-{G}eometry {IGA} {M}esh {G}eneration: application to structural vibrations}, YEAR = {2024}, DOI = {10.1007/s00466-023-02432-6}, NOTE = {\textit{Computational Mechanics}, published online, doi: 10.1007/s00466-023-02432-6} } Abstract:
We present an isogeometric analysis (IGA) framework for structural vibrations involving complex geometries. The framework is based on the Complex-Geometry IGA Mesh Generation (CGIMG) method. The CGIMG process is flexible and can accommodate, without a major effort, challenging complex-geometry applications in computational mechanics. To demonstrate how the new IGA framework significantly increases the computational effectiveness, in a set of structural-vibration test computations, we compare the accuracies attained by the IGA and finite element (FE) method as the number of degrees-of-freedom is increased. The results show that the NURBS meshes lead to faster convergence and higher accuracy compared to both linear and quadratic FE meshes. The clearly defined IGA mesh generation process and significant per-degree-of-freedom accuracy advantages of IGA over FE discretization make IGA more accessible, reliable, and attractive in applications of both academic and industrial interest. We note that the accuracy of a structural mechanics discretization, which may be assessed through eigenfrequency analysis, plays an important role in the overall accuracy of fluid–structure interaction computations.

[126]

Y. Liu, K. Takizawa, and T.E. Tezduyar, “High-resolution 3D computation of time-periodic long-wake flows with the Carrier-Domain Method and Space–Time Variational Multiscale method with isogeometric discretization”, Computational Mechanics, published online, doi: 10.1007/s00466-023-02419-3 (2024), 10.1007/s00466-023-02419-3
@UNPUBLISHED{LiuYang23a, AUTHOR = {Y.~Liu and K.~Takizawa and T. E.~Tezduyar}, TITLE = {High-resolution {3D} computation of time-periodic long-wake flows with the {C}arrier-{D}omain {M}ethod and {S}pace–{T}ime {V}ariational {M}ultiscale method with isogeometric discretization}, YEAR = {2024}, DOI = {10.1007/s00466-023-02419-3}, NOTE = {\textit{Computational Mechanics}, published online, doi: 10.1007/s00466-023-02419-3} } Abstract:
The Carrier-Domain Method was introduced for high-resolution computation of time-periodic long-wake flows. The cost-effectiveness of the method makes such computations practical in 3D. A short segment of the wake domain, the carrier domain, moves in the free-stream direction, from the beginning of the long wake domain to the end. The data at the moving inflow plane comes from the time-periodic data computed at an earlier position of the carrier domain. With the high mesh resolution that can easily be afforded over the short domain segment, the wake flow patterns can be carried, with superior accuracy, far downstream. Computing the long-wake flow with a high-resolution moving mesh that covers a short segment of the wake domain at any instant during the computation would certainly be far more cost-effective than computing it with a high-resolution fixed mesh that covers the entire length. We present high-resolution 3D computation of time-periodic long-wake flow for a cylinder and a wind turbine, both computed with isogeometric discretization and the Space–Time Variational Multiscale method. In the isogeometric discretization, the basis functions are quadratic NURBS in space and linear in time. The cylinder flow is at Reynolds number 100. At this Reynolds number, the flow has an easily discernible vortex shedding period. The wake flow is computed up to 350 diameters downstream of the cylinder, far enough to see the secondary vortex street. In the wind turbine long-wake flow computation, the velocity data at the inflow boundary of the wake domain comes from an earlier wind turbine computation, with the turbine rotor having a diameter of 126m, extracted by projection from a plane located 10m downstream of the turbine. The wake flow is computed up to 482m downstream of the wind turbine. In both the cylinder and wind turbine wake flow computations, the flow patterns obtained with the full domain and carrier domain show a near-perfect match, clearly demonstrating the effectiveness and practicality of the Carrier-Domain Method in high-resolution 3D computation of time-periodic long-wake flows.

[125]

K. Takizawa and T.E. Tezduyar, “Space–time flow computation with boundary layer and contact representation: a 10-year history”, Computational Mechanics, published online, doi: 10.1007/s00466-023-02379-8 (2023), 10.1007/s00466-023-02379-8
@UNPUBLISHED{Takizawa23b, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {Space–time flow computation with boundary layer and contact representation: a 10-year history}, YEAR = {2023}, DOI = {10.1007/s00466-023-02379-8}, NOTE = {\textit{Computational Mechanics}, published online, doi: 10.1007/s00466-023-02379-8} } Abstract:
In computation of flow problems with moving solid surfaces, moving-mesh methods such as the space–time (ST) variational multiscale method enable mesh-resolution control near the solid surfaces and thus high-resolution boundary-layer representation. There was, however, a perception that in computations where the solid surfaces come into contact, high-resolution boundary-layer representation and actual-contact representation without leaving a mesh protection opening between the solid surfaces were mutually exclusive objectives in a practical sense. The introduction of the ST topology change (ST-TC) method in 2013 changed the perception. The two objectives were no longer mutually exclusive. The ST-TC makes moving-mesh computation possible even without leaving a mesh protection opening. The contact is represented as an actual contact and the boundary layer is represented with high resolution. Elements collapse or are reborn as needed, and that is attainable in the ST framework while retaining the computational efficiency at a practical level. The ST-TC now has a 10-year history of achieving the two objectives that were long seen as mutually exclusive. With the ST-TC and other ST computational methods introduced before and after, it has been possible to address many of the challenges encountered in conducting flow analysis with boundary layer and contact representation, in the presence of additional intricacies such as geometric complexity, isogeometric discretization, and rotation or deformation of the solid surfaces. The flow analyses conducted with these ST methods include car and tire aerodynamics with road contact and tire deformation and ventricle-valve-aorta flow. To help widen awareness of these methods and what they can do, we provide an overview of the methods, including those formulated in the context of isogeometric analysis, and the computations performed over the 10-year history of the ST-TC.

[124]

T.E. Tezduyar, K. Takizawa, and Y. Bazilevs, “Isogeometric analysis in computation of complex-geometry flow problems with moving boundaries and interfaces”, Mathematical Models and Methods in Applied Sciences, 34 (2024) 7–56, 10.1142/S0218202524400013
Times Cited in Web of Science Core Collection: 1, Times Cited in Scopus: 2
@ARTICLE{Tezduyar23b, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and Y.~Bazilevs}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Isogeometric analysis in computation of complex-geometry flow problems with moving boundaries and interfaces}, VOLUME = {34}, YEAR = {2024}, PAGES = {7–56}, DOI = {10.1142/S0218202524400013} } Abstract:
Flows with moving boundaries and interfaces (MBI) are a large class of problems that include fluid-particle and fluid-structure interactions, and in broader terms, moving solid surfaces. They also include multi-fluid flows, and as a special case of that, free-surface flows, sometimes in combination with moving solid surfaces. In some classes of MBI problems the solid surfaces could be in fast, linear or rotational relative motion or could come into contact. In almost all real-world applications, the solid surfaces would have complex geometries. All these problems are frequently encountered in engineering analysis and design, pose some of the most formidable computational challenges, and have a common core computational technology need. Bringing solution and analysis to them motivated the development of a good number of core computational methods and special methods targeting specific classes of MBI problems. This paper is an overview of some of those core and special methods. The focus is on isogeometric analysis, complex geometries, incompressible-flow Space-Time Variational Multiscale (ST-VMS) and Arbitrary Lagrangian-Eulerian VMS (ALE-VMS) methods, compressible-flow ST Streamline-Upwind/Petrov-Galerkin (ST-SUPG) and ALE-SUPG methods, and some of the special methods developed in connection with these core ST and ALE methods. The incompressible-flow ST-VMS and ALE-VMS and compressible-flow ST-SUPG and ALE-SUPG are moving-mesh methods, where the mesh moves to have mesh-resolution control near the fluid-solid interfaces, enabling high-resolution boundary-layer representation, an essential feature when the accuracy in representing the boundary layer is a priority. The computational examples presented are car and tire aerodynamics with road contact and tire deformation, ventricle-valve-aorta flow, and gas turbine flow.

[123]

T.E. Tezduyar and K. Takizawa, “Space–time computational flow analysis: Unconventional methods and first-ever solutions”, Computer Methods in Applied Mechanics and Engineering, 417 (2023) 116137, 10.1016/j.cma.2023.116137
Times Cited in Web of Science Core Collection: 2, Times Cited in Scopus: 2
@ARTICLE{Tezduyar23a, AUTHOR = {T. E.~Tezduyar and K.~Takizawa}, JOURNAL = {Computer Methods in Applied Mechanics and Engineering}, TITLE = {Space–Time Computational Flow Analysis: {U}nconventional Methods and First-Ever Solutions}, VOLUME = {417}, YEAR = {2023}, PAGES = {116137}, DOI = {10.1016/j.cma.2023.116137} } Abstract:
The Deforming-Spatial-Domain/Stabilized Space–Time (DSD/SST) method was introduced in 1990 as a moving-mesh method for computational analysis of flows with moving boundaries and interfaces (MBI), which is a wide class of problems that includes fluid–particle and fluid–structure interactions and free-surface and multi-fluid flows. The method was inspired by Thomas Hughes’s 1987 work on space–time finite element methods for elastodynamics. The original DSD/SST method is now called “ST-SUPS”, reflecting its stabilization components, which are the Streamline-Upwind/Petrov–Galerkin (SUPG) method, pioneered by Hughes, and the Pressure-Stabilizing/Petrov–Galerkin (PSPG) method, inspired by Hughes’s work on a Stokes-flow Petrov–Galerkin formulation allowing equal-order interpolations for velocity and pressure. Hughes’s work on the residual-based variational multiscale (RBVMS) method inspired the ST-VMS method, which is the VMS version of the DSD/SST. A number of special methods were introduced in connection with the core methods ST-SUPS and ST-VMS. Hughes’s work on isogeometric analysis (IGA) inspired one of those special methods, the “ST-IGA”, with IGA basis functions not only in space but also in time. The core and special ST methods enabled first-ever solutions in some of the most challenging classes of MBI problems, including particle-laden flows, spacecraft parachute fluid–structure interactions, and car and tire aerodynamics. We provide an overview of the ST methods inspired by Hughes’s work and highlight some of the first-ever solutions in these three classes of MBI problems.

[122]

K. Takizawa, Y. Otoguro, and T.E. Tezduyar, “Variational multiscale method stabilization parameter calculated from the strain-rate tensor”, Mathematical Models and Methods in Applied Sciences, 33 (2023) 1661–1691, 10.1142/S0218202523500380
Times Cited in Web of Science Core Collection: 4, Times Cited in Scopus: 5
@ARTICLE{Takizawa23a, AUTHOR = {K.~Takizawa and Y.~Otoguro and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Variational multiscale method stabilization parameter calculated from the strain-rate tensor}, VOLUME = {33}, NUMBER = {8}, YEAR = {2023}, PAGES = {1661–1691}, DOI = {10.1142/S0218202523500380} } Abstract:
The stabilization parameters of the methods like the Streamline-Upwind/Petrov-Galerkin, Pressure-Stabilizing/Petrov-Galerkin, and the Variational Multiscale method typically involve two local length scales. They are the advection and diffusion length scales, appearing in the expressions for the advective and diffusive limits of the stabilization parameter. The advection length scale has always been in the flow direction. The diffusion length scales in use have mostly been just element-geometry-dependent, but there is good justification for also making that direction-dependent, so that the spatial variation of the solution is taken into account somehow. The length scale in the solution-gradient direction, which was introduced in 2001, was intended for making sure that near solid surfaces, the element length in the surface-normal direction is selected even if that is not the minimum element length. It was also intended for making sure that in a 2D computation with a 3D mesh, there would be no dependence on the element length in the third direction. With the same objectives, and with better invariance properties, we are now introducing the direction-dependent diffusion length scale calculated from the strain-rate tensor. We accomplish those objectives, get invariance with respect to switching to a different inertial reference frame, and the element length in the surface-normal direction, even when the surface is undergoing rotation, is selected as the diffusion length scale.

[121]

Y. Bazilevs, K. Takizawa, T.E. Tezduyar, A. Korobenko, T. Kuraishi, and Y. Otoguro, “Computational aerodynamics with isogeometric analysis”, Journal of Mechanics, 39 (2023) 24–39, 10.1093/jom/ufad002
Times Cited in Web of Science Core Collection: 5, Times Cited in Scopus: 8
@ARTICLE{Bazilevs22a, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar and A.~Korobenko and T.~Kuraishi and Y.~Otoguro}, JOURNAL = {Journal of Mechanics}, TITLE = {Computational Aerodynamics With Isogeometric Analysis}, VOLUME = {39}, YEAR = {2023}, PAGES = {24–39}, DOI = {10.1093/jom/ufad002} } Abstract:
The superior accuracy isogeometric analysis (IGA) brought to computations in fluid and solid mechanics has been yielding higher fidelity in computational aerodynamics. The increased accuracy we achieve with the IGA is in the flow solution, in representing the problem geometry, and, when we use the IGA basis functions also in time in a space-time (ST) framework, in representing the motion of solid surfaces. It is of course as part of a set of methods that the IGA has been very effective in computational aerodynamics, including complex-geometry aerodynamics. The set of methods we have been using can be categorized into those that serve as a core method, those that increase the accuracy, and those that widen the application range. The core methods are the residual-based variational multiscale (VMS), ST-VMS and arbitrary Lagrangian-Eulerian VMS methods. The IGA and ST-IGA are examples of the methods that increase the accuracy. The complex-geometry IGA mesh generation method is an example of the methods that widen the application range. The ST Topology Change method is another example of that. We provide an overview of these methods for IGA-based computational aerodynamics and present examples of the computations performed. In computational flow analysis with moving solid surfaces and contact between the solid surfaces, it is a challenge to represent the boundary layers with an accuracy attributed to moving-mesh methods and represent the contact without leaving a mesh protection gap.

[120]

T. Terahara, K. Takizawa, R. Avsar, and T.E. Tezduyar, “T-splines computational membrane–cable structural mechanics with continuity and smoothness: II. Spacecraft parachutes”, Computational Mechanics, 71 (2023) 677–686, 10.1007/s00466-022-02265-9
Times Cited in Web of Science Core Collection: 4, Times Cited in Scopus: 7
@ARTICLE{Terahara22c, AUTHOR = {T.~Terahara and K.~Takizawa and R.~Avsar and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {T-Splines Computational Membrane–Cable Structural Mechanics with Continuity and Smoothness: {II}. {S}pacecraft parachutes}, VOLUME = {71}, YEAR = {2023}, PAGES = {677–686}, DOI = {10.1007/s00466-022-02265-9} } Abstract:
In this second part of a two-part article, we present spacecraft parachute structural mechanics computations with the T-splines computational method introduced in the first part. The method and its implementation, which was also given in the first part, are for computations where structures with different parametric dimensions are connected with continuity and smoothness. The basis functions of the method were derived in the context of connecting structures with 2D and 1D parametric dimensions. In the first part, the 2D structure was referred to as “membrane” and the 1D structure as “cable.” The method and its implementation, however, are certainly applicable also to other 2D–1D cases, and the test computations presented in the first part included shell–cable structures. Similarly, the spacecraft parachute computations presented here are with both the membrane and shell models of the parachute canopy fabric. The computer model used in the computations is for a subscale, wind-tunnel version of the Disk–Gap–Band parachute. The computations demonstrate the effectiveness of the method in 2D–1D structural mechanics computation of spacecraft parachutes.

[119]

T. Terahara, K. Takizawa, and T.E. Tezduyar, “T-splines computational membrane–cable structural mechanics with continuity and smoothness: I. Method and implementation”, Computational Mechanics, 71 (2023) 657–675, 10.1007/s00466-022-02256-w
Times Cited in Web of Science Core Collection: 4, Times Cited in Scopus: 9
@ARTICLE{Terahara22b, AUTHOR = {T.~Terahara and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {T-Splines Computational Membrane–Cable Structural Mechanics with Continuity and Smoothness: {I}. {M}ethod and Implementation}, VOLUME = {71}, YEAR = {2023}, PAGES = {657–675}, DOI = {10.1007/s00466-022-02256-w} } Abstract:
We present a T-splines computational method and its implementation where structures with different parametric dimensions are connected with continuity and smoothness. We derive the basis functions in the context of connecting structures with 2D and 1D parametric dimensions. Derivation of the basis functions with a desired smoothness involves proper selection of a scale factor for the knot vector of the 1D structure and results in new control-point locations. While the method description focuses on C and C1 continuity, paths to higher-order continuity are marked where needed. In presenting the method and its implementation, we refer to the 2D structure as “membrane” and the 1D structure as “cable.” It goes without saying that the method and its implementation are applicable also to other 2D–1D cases, such as shell–cable and shell–beam structures. We present test computations not only for membrane–cable structures but also for shell–cable structures. The computations demonstrate how the method performs.

[118]

K. Takizawa, Y. Bazilevs, and T.E. Tezduyar, “Isogeometric discretization methods in computational fluid mechanics”, Mathematical Models and Methods in Applied Sciences, 32 (2022) 2359–2370, 10.1142/S0218202522020018
Times Cited in Web of Science Core Collection: 7, Times Cited in Scopus: 7
@ARTICLE{Takizawa22c, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Isogeometric Discretization Methods in Computational Fluid Mechanics}, VOLUME = {32}, NUMBER = {12}, YEAR = {2022}, PAGES = {2359–2370}, DOI = {10.1142/S0218202522020018} } Abstract:
In this lead article of the special issue, we provide a brief summary of the research developments in Isogeometric Analysis (IGA) for Computational Fluid Dynamics (CFD). We focus on the use of IGA in combination with stabilized and variational multiscale methods in fluids. We highlight the key developments and present results in IGA-based CFD that makes this technology attractive for the computational analysis of complex, unsteady and, often turbulent, flows encountered in modern science and engineering applications. We cover both incompressible and compressible flows, numerical method development and performance evaluation using benchmark problems, and applications ranging from stratified environmental flows over complex terrains to concrete-blast fluid–structure interaction. A short synopsis of each article in the special issue is also provided to help reader quickly see what is in the special issue.

[117]

Y. Liu, K. Takizawa, T.E. Tezduyar, T. Kuraishi, and Y. Zhang, “Carrier-domain method for high-resolution computation of time-periodic long-wake flows”, Computational Mechanics, 71 (2023) 169–190, 10.1007/s00466-022-02230-6
Times Cited in Web of Science Core Collection: 8, Times Cited in Scopus: 13
@ARTICLE{LiuYang22b, AUTHOR = {Y.~Liu and K.~Takizawa and T. E.~Tezduyar and T.~Kuraishi and Y.~Zhang}, JOURNAL = {Computational Mechanics}, TITLE = {Carrier-Domain Method for High-Resolution Computation of Time-Periodic Long-Wake Flows}, VOLUME = {71}, YEAR = {2023}, PAGES = {169–190}, DOI = {10.1007/s00466-022-02230-6} } Abstract:
We are introducing the Carrier-Domain Method (CDM) for high-resolution computation of time-periodic long-wake flows, with cost-effectives that makes the computations practical. The CDM is closely related to the Multidomain Method, which was introduced 24 years ago, originally intended also for cost-effective computation of long-wake flows and later extended in scope to cover additional classes of flow problems. In the CDM, the computational domain moves in the free-stream direction, with a velocity that preserves the outflow nature of the downstream computational boundary. As the computational domain is moving, the velocity at the inflow plane is extracted from the velocity computed earlier when the plane’s current position was covered by the moving domain. The inflow data needed at an instant is extracted from one or more instants going back in time as many periods. Computing the long-wake flow with a high-resolution moving mesh that has a reasonable length would certainly be far more cost-effective than computing it with a fixed mesh that covers the entire length of the wake. We are also introducing a CDM version where the computational domain moves in a discrete fashion rather than a continuous fashion. To demonstrate how the CDM works, we compute, with the version where the computational domain moves in a continuous fashion, the 2D flow past a circular cylinder at Reynolds number 100. At this Reynolds number, the flow has an easily discernible vortex shedding frequency and widely published lift and drag coefficients and Strouhal number. The wake flow is computed up to 350 diameters downstream of the cylinder, far enough to see the secondary vortex street. The computations are performed with the Space–Time Variational Multiscale method and isogeometric discretization; the basis functions are quadratic NURBS in space and linear in time. The results show the power of the CDM in high-resolution computation of time-periodic long-wake flows.

[116]

T. Kuraishi, Z. Xu, K. Takizawa, T.E. Tezduyar, and S. Yamasaki, “High-resolution multi-domain space–time isogeometric analysis of car and tire aerodynamics with road contact and tire deformation and rotation”, Computational Mechanics, 70 (2022) 1257–1279, 10.1007/s00466-022-02228-0
Times Cited in Web of Science Core Collection: 11, Times Cited in Scopus: 18
@ARTICLE{Kuraishi22c, AUTHOR = {T.~Kuraishi and Z.~Xu and K.~Takizawa and T. E.~Tezduyar and S.~Yamasaki}, JOURNAL = {Computational Mechanics}, TITLE = {High-Resolution Multi-Domain Space–Time Isogeometric Analysis of Car and Tire Aerodynamics with Road Contact and Tire Deformation and Rotation}, VOLUME = {70}, YEAR = {2022}, PAGES = {1257–1279}, DOI = {10.1007/s00466-022-02228-0} } Abstract:
We are presenting high-resolution space–time (ST) isogeometric analysis of car and tire aerodynamics with near-actual tire geometry, road contact, and tire deformation and rotation. The focus in the high-resolution computation is on the tire aerodynamics. The high resolution is not only in space but also in time. The influence of the aerodynamics of the car body comes, in the framework of the Multidomain Method (MDM), from the global computation with near-actual car body and tire geometries, carried out earlier with a reasonable mesh resolution. The high-resolution local computation, carried out for the left set of tires, takes place in a nested MDM sequence over three subdomains. The first subdomain contains the front tire. The second subdomain, with the inflow velocity from the first subdomain, is for the front-tire wake flow. The third subdomain, with the inflow velocity from the second subdomain, contains the rear tire. All other boundary conditions for the three subdomains are extracted from the global computation. The full computational framework is made of the ST Variational Multiscale (ST-VMS) method, ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods, ST Isogeometric Analysis (ST-IGA), integrated combinations of these ST methods, element-based mesh relaxation (EBMR), methods for calculating the stabilization parameters and related element lengths targeting IGA discretization, Complex-Geometry IGA Mesh Generation (CGIMG) method, MDM, and the “ST-C” data compression. Except for the last three, these methods were used also in the global computation, and they are playing the same role in the local computation. The ST-TC, for example, as in the global computation, is making the ST moving-mesh computation possible even with contact between the tire and the road, thus enabling high-resolution flow representation near the tire. The CGIMG is making the IGA mesh generation for the complex geometries less arduous. The MDM is reducing the computational cost by focusing the high-resolution locally to where it is needed and also by breaking the local computation into its consecutive portions. The ST-C data compression is making the storage of the data from the global computation less burdensome. The car and tire aerodynamics computation we present shows the effectiveness of the high-resolution computational analysis framework we have built for this class of problems.

[115]

T. Kuraishi, K. Takizawa, and T.E. Tezduyar, “Boundary layer mesh resolution in flow computation with the Space–Time Variational Multiscale method and isogeometric discretization”, Mathematical Models and Methods in Applied Sciences, 32 (2022) 2401–2443, 10.1142/S0218202522500567
Times Cited in Web of Science Core Collection: 12, Times Cited in Scopus: 16
@ARTICLE{Kuraishi22b, AUTHOR = {T.~Kuraishi and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Boundary layer mesh resolution in flow computation with the {S}pace–{T}ime {V}ariational {M}ultiscale method and isogeometric discretization}, VOLUME = {32}, NUMBER = {12}, YEAR = {2022}, PAGES = {2401–2443}, DOI = {10.1142/S0218202522500567} } Abstract:
We present an extensive study on boundary layer mesh resolution in flow computation with the Space-Time Variational Multiscale (ST-VMS) method and isogeometric discretization. The study is in the context of 2D flow past a circular cylinder, at Reynolds number ranging from 102 to 106. It was motivated by the need to have in tire aerodynamics a better understanding of the mesh resolution requirements near the tire surface. The focus in the study is on the normal-direction element length for the first layer of elements near the cylinder, with that length varying by a refinement factor ranging from 2 to 40. The evaluation is based mostly on the velocity profile near the cylinder. As the element length for the first layer is varied, the element lengths for the other layers of the disk-shaped inner mesh are adjusted, with no increase in the number of elements for the refinement factors 2, 3, and 4, and with modest increases only in the radial direction for refinement factors beyond that. The computations are performed with quadratic NURBS basis functions in space and linear basis functions in time. The expressions for the stabilization parameters used in the ST-VMS and for the related local lengths scales are those targeting isogeometric discretization, introduced in recent years. The mesh resolution study is based mostly on the strong enforcement of the Dirichlet boundary conditions on the cylinder, but also includes some computations with the weakly-enforced conditions. We expect that the data generated and observations made will be helpful in setting proper near-surface mesh resolution in VMS-based computations with isogeometric discretization, not only for cylindrical shapes but also for comparable geometries. We furthermore expect that although the data generated and observations made are based on computations with nonmoving meshes, they will also be applicable to computations with moving meshes where the mesh around the solid surface rotates with the surface in the framework of the ST Slip Interface method.

[114]

Y. Liu, K. Takizawa, Y. Otoguro, T. Kuraishi, and T.E. Tezduyar, “Flow computation with the space–time isogeometric analysis and higher-order basis functions in time”, Mathematical Models and Methods in Applied Sciences, 32 (2022) 2445–2475, 10.1142/S0218202522500579
Times Cited in Web of Science Core Collection: 11, Times Cited in Scopus: 15
@ARTICLE{LiuYang22a, AUTHOR = {Y.~Liu and K.~Takizawa and Y.~Otoguro and T.~Kuraishi and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Flow Computation with the Space–Time Isogeometric Analysis and Higher-Order Basis Functions in Time}, VOLUME = {32}, NUMBER = {12}, YEAR = {2022}, PAGES = {2445–2475}, DOI = {10.1142/S0218202522500579} } Abstract:
We present method-evaluation incompressible-flow computations with Space-Time Isogeometric Analysis (ST-IGA) and higher-order basis functions in time. The computational-methods platform is made of the ST Variational Multiscale (ST-VMS) method, the ST-IGA with IGA basis functions in space and time, and local length scales and stabilization parameters targeting isogeometric discretization. The computations are for 2D flow past a circular cylinder at Reynolds number 100, which has an easily discernible vortex shedding frequency and widely published lift and drag coefficients and Strouhal number. We compute with quadratic basis functions in space and polynomial orders of 1, 2, 3, and 4 in time, for four different time-step sizes, and with six different sets of expressions for the stabilization parameters. The computations yield a comprehensive set of method-evaluation data that can serve as reference. They also show computational-cost efficiency in using higher-order functions in time.

[113]

Y. Taniguchi, K. Takizawa, Y. Otoguro, and T.E. Tezduyar, “A hyperelastic extended Kirchhoff–Love shell model with out-of-plane normal stress: I. Out-of-plane deformation”, Computational Mechanics, 70 (2022) 247–280, 10.1007/s00466-022-02166-x
Times Cited in Web of Science Core Collection: 14, Times Cited in Scopus: 18
@ARTICLE{Taniguchi22a, AUTHOR = {Y.~Taniguchi and K.~Takizawa and Y.~Otoguro and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {A hyperelastic extended {K}irchhoff–{L}ove shell model with out-of-plane normal stress: {I}. {O}ut-of-plane deformation}, VOLUME = {70}, YEAR = {2022}, PAGES = {247–280}, DOI = {10.1007/s00466-022-02166-x} } Abstract:
This is the first part of a two-part article on a hyperelastic extended Kirchhoff–Love shell model with out-of-plane normal stress. We present the derivation of the new model, with focus on the mechanics of the out-of-plane deformation. Accounting for the out-of-plane normal stress distribution in the out-of-plane direction affects the accuracy in calculating the deformed-configuration out-of-plane position, and consequently the nonlinear response of the shell. The improvement is beyond what we get from accounting for the out-of-plane deformation mapping. By accounting for the out-of-plane normal stress, the traction acting on the shell can be specified on the upper and lower surfaces separately. With that, the new model is free from the “midsurface” location in terms of specifying the traction. We also present derivations related to the variation of the kinetic energy and the form of specifying the traction and moment acting on the upper and lower surfaces and along the edges. We present test computations for unidirectional plate bending, plate saddle deformation, and pressurized cylindrical and spherical shells. We use the neo-Hookean and Fung’s material models, for the compressible- and incompressible-material cases, and with the out-of-plane normal stress and without, which is the plane-stress case.

[112]

T. Terahara, T. Kuraishi, K. Takizawa, and T.E. Tezduyar, “Computational flow analysis with boundary layer and contact representation: II. Heart valve flow with leaflet contact”, Journal of Mechanics, 38 (2022) 185–194, 10.1093/jom/ufac013
Times Cited in Web of Science Core Collection: 20, Times Cited in Scopus: 26
@ARTICLE{Terahara22a, AUTHOR = {T.~Terahara and T.~Kuraishi and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Journal of Mechanics}, TITLE = {Computational flow analysis with boundary layer and contact representation: {II}. {H}eart valve flow with leaflet contact}, VOLUME = {38}, YEAR = {2022}, PAGES = {185–194}, DOI = {10.1093/jom/ufac013} } Abstract:
In this second part of a two-part article, we provide an overview of the heart valve flow analyses conducted with boundary layer and contact representation, made possible with the space-time (ST) computational methods described in the first part. With these ST methods, we are able to represent the boundary layers near moving solid surfaces, including the valve leaflet surfaces, with the accuracy one gets from moving-mesh methods and without the need for leaving a mesh protection gap between the surfaces coming into contact. The challenge of representing the contact between the leaflets without giving up on high-resolution flow representation near the leaflet surfaces has been overcome. The other challenges that have been overcome include the complexities of a near-actual valve geometry, having in the computational model a left ventricle with an anatomically realistic motion and an aorta from CT scans and maintaining the flow stability at the inflow of the ventricle-valve-aorta sequence, where we have a traction boundary condition during part of the cardiac cycle.

[111]

T. Kuraishi, T. Terahara, K. Takizawa, and T.E. Tezduyar, “Computational flow analysis with boundary layer and contact representation: I. Tire aerodynamics with road contact”, Journal of Mechanics, 38 (2022) 77–87, 10.1093/jom/ufac009
Times Cited in Web of Science Core Collection: 16, Times Cited in Scopus: 22
@ARTICLE{Kuraishi22a, AUTHOR = {T.~Kuraishi and T.~Terahara and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Journal of Mechanics}, TITLE = {Computational flow analysis with boundary layer and contact representation: {I}. {T}ire aerodynamics with road contact}, VOLUME = {38}, YEAR = {2022}, PAGES = {77–87}, DOI = {10.1093/jom/ufac009} } Abstract:
In computational flow analysis with moving solid surfaces and contact between the solid surfaces, it is a challenge to represent the boundary layers with an accuracy attributed to moving-mesh methods and to represent the contact without leaving a mesh protection gap. The space-time topology change (ST-TC) method, introduced in 2013, makes moving-mesh computation possible even when we have contact between moving solid surfaces or other kinds of flow-domain TC. The contact is represented without giving up on high-resolution flow representation near the moving surfaces. With the ST-TC and other ST computational methods introduced before and after, it has been possible to address many of the challenges encountered in conducting this class of flow analysis in the presence of additional complexities such as geometric complexity, rotation or deformation of the solid surfaces and the multiscale nature of the flow. In this first part of a two-part article, we provide an overview of the methods that made all that possible. We also provide an overview of the computations performed for tire aerodynamics with challenges that include the complexity of a near-actual tire geometry with grooves, road contact, tire deformation and rotation, road roughness and fluid films.

[110]

T. Kuraishi, S. Yamasaki, K. Takizawa, T.E. Tezduyar, Z. Xu, and R. Kaneko, “Space–time isogeometric analysis of car and tire aerodynamics with road contact and tire deformation and rotation”, Computational Mechanics, 70 (2022) 49–72, 10.1007/s00466-022-02155-0
Times Cited in Web of Science Core Collection: 17, Times Cited in Scopus: 22
@ARTICLE{Kuraishi21c, AUTHOR = {T.~Kuraishi and S.~Yamasaki and K.~Takizawa and T. E.~Tezduyar and Z.~Xu and R.~Kaneko}, JOURNAL = {Computational Mechanics}, TITLE = {Space–time isogeometric analysis of car and tire aerodynamics with road contact and tire deformation and rotation}, VOLUME = {70}, YEAR = {2022}, PAGES = {49–72}, DOI = {10.1007/s00466-022-02155-0} } Abstract:
We present a space–time (ST) isogeometric analysis framework for car and tire aerodynamics with road contact and tire deformation and rotation. The geometries of the computational models for the car body and tires are close to the actual geometries. The computational challenges include i) the complexities of these geometries, ii) the tire rotation, iii) maintaining accurate representation of the boundary layers near the tire while being able to deal with the flow-domain topology change created by the road contact, iv) the turbulent nature of the flow, v) the aerodynamic interaction between the car body and the tires, and vi) NURBS mesh generation for the complex geometries. The computational framework is made of the ST Variational Multiscale (ST-VMS) method, ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods, ST Isogeometric Analysis (ST-IGA), integrated combinations of these ST methods, NURBS Surface-to-Volume Guided Mesh Generation (NSVGMG) method, and the element-based mesh relaxation (EBMR). The ST context provides higher-order accuracy in general, the VMS feature of the ST-VMS addresses the challenge created by the turbulent nature of the flow, and the moving-mesh feature of the ST context enables high-resolution flow computation near the moving fluid–solid interfaces. The ST-SI enables moving-mesh computation with the tire rotating. The mesh covering the tire rotates with it, and the SI between the rotating mesh and the rest of the mesh accurately connects the two sides of the solution. The ST-TC enables moving-mesh computation even with the TC created by the contact between the tire and the road. It deals with the contact while maintaining high-resolution flow representation near the tire. Integration of the ST-SI and ST-TC enables high-resolution representation even though parts of the SI are coinciding with the tire and road surfaces. It also enables dealing with the tire–road contact location change and contact sliding. By integrating the ST-IGA with the ST-SI and ST-TC, in addition to having a more accurate representation of the tire geometry and increased accuracy in the flow solution, the element density in the tire grooves and in the narrow spaces near the contact areas is kept at a reasonable level. The NSVGMG enables NURBS mesh generation for the complex car and tire geometries, and the EBMR improves the quality of the meshes. The car and tire aerodynamics computation we present shows the effectiveness of the analysis framework we have built.

[109]

F. Zhang, T. Kuraishi, K. Takizawa, and T.E. Tezduyar, “Wind turbine wake computation with the ST-VMS method and isogeometric discretization: Directional preference in spatial refinement”, Computational Mechanics, 69 (2022) 1031–1040, 10.1007/s00466-021-02129-8
Times Cited in Web of Science Core Collection: 11, Times Cited in Scopus: 13
@ARTICLE{ZhangFulin21a, AUTHOR = {F.~Zhang and T.~Kuraishi and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Wind turbine wake computation with the {ST-VMS} method and isogeometric discretization: {D}irectional preference in spatial refinement}, VOLUME = {69}, YEAR = {2022}, PAGES = {1031–1040}, DOI = {10.1007/s00466-021-02129-8} } Abstract:
In this sequel to a two-part article on wind turbine wake computation with the Space–Time Variational Multiscale (ST-VMS) method and ST isogeometric discretization, we study directional preference in spatial refinement. We evaluate the wake computation accuracy of different combinations of mesh resolutions in the free-stream and cross-flow directions. We also evaluate the accuracy of different combinations of B-spline polynomial orders in those directions. The computational framework is the same as in the two-part article. It is made of, in addition to the ST-VMS and ST isogeometric discretization, the Multidomain Method (MDM). It enables accurate representation of the turbine long-wake vortex patterns in a computationally efficient way. Because of the ST context, the computational framework has higher-order accuracy to begin with; because of the VMS feature, it addresses the computational challenges associated with the multiscale nature of the flow; with the isogeometric discretization, it provides increased accuracy in the flow solution; and with the MDM, a long wake can be computed over a sequence of subdomains, instead of a single, long domain, thus reducing the computational cost. Also with the MDM, the computation over a downstream subdomain can start several turbine rotations after the computation over the upstream subdomain starts, thus reducing the computational cost even more. In the computations presented here, as in the two-part article, the velocity data on the inflow plane comes from a previous wind turbine computation, extracted by projection from a plane located 10 m downstream of the turbine, which has a diameter of 126 m. The directional-refinement studies involve four different spatial resolutions, two different B-spline polynomial orders, and two different temporal resolutions. The studies show that there is some preference for refinement in the cross-flow directions.

[108]

T. Kuraishi, F. Zhang, K. Takizawa, and T.E. Tezduyar, “Wind turbine wake computation with the ST-VMS method, isogeometric discretization and multidomain method: II. Spatial and temporal resolution”, Computational Mechanics, 68 (2021) 175–184, 10.1007/s00466-021-02025-1
Times Cited in Web of Science Core Collection: 16, Times Cited in Scopus: 21
@ARTICLE{Kuraishi21b, AUTHOR = {T.~Kuraishi and F.~Zhang and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Wind turbine wake computation with the {ST-VMS} method, isogeometric discretization and multidomain method: {II}. {S}patial and temporal resolution}, VOLUME = {68}, YEAR = {2021}, PAGES = {175–184}, DOI = {10.1007/s00466-021-02025-1} } Abstract:
In this second part of a two-part article, we present extensive studies on spatial and temporal resolution in wind turbine wake computation with the computational framework presented in the first part. The framework, which is made of the Space–Time Variational Multiscale (ST-VMS) method, ST isogeometric discretization, and the Multidomain Method (MDM), enables accurate representation of the turbine long-wake vortex patterns in a computationally efficient way. Because of the ST context, the framework has higher-order accuracy to begin with; because of the VMS feature of the ST-VMS, it addresses the computational challenges associated with the multiscale nature of the flow; with the isogeometric discretization, it provides increased accuracy in the flow solution; and with the MDM, a long wake can be computed over a sequence of subdomains, instead of a single, long domain, thus reducing the computational cost. Also with the MDM, the computation over a downstream subdomain can start several turbine rotations after the computation over the upstream subdomain starts, thus reducing the computational cost even more. In the computations presented here, the velocity data on the inflow plane comes from a previous wind turbine computation, extracted by projection from a plane located 10 m downstream of the turbine, which has a diameter of 126 m. The resolution studies involve three different spatial resolutions and two different temporal resolutions. The studies show that the computational framework provides, with a practical level of efficiency, high-fidelity solutions in wind turbine long-wake computations.

[107]

T. Kuraishi, F. Zhang, K. Takizawa, and T.E. Tezduyar, “Wind turbine wake computation with the ST-VMS method, isogeometric discretization and multidomain method: I. Computational framework”, Computational Mechanics, 68 (2021) 113–130, 10.1007/s00466-021-02022-4
Times Cited in Web of Science Core Collection: 16, Times Cited in Scopus: 20
@ARTICLE{Kuraishi21a, AUTHOR = {T.~Kuraishi and F.~Zhang and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Wind turbine wake computation with the {ST-VMS} method, isogeometric discretization and multidomain method: {I}. {C}omputational framework}, VOLUME = {68}, YEAR = {2021}, PAGES = {113–130}, DOI = {10.1007/s00466-021-02022-4} } Abstract:
In this first part of a two-part article, we present a framework for wind turbine wake computation. The framework is made of the Space–Time Variational Multiscale (ST-VMS) method, ST isogeometric discretization, and the Multidomain Method (MDM). The ST context provides higher-order accuracy in general, and the VMS feature of the ST-VMS addresses the computational challenges associated with the multiscale nature of the flow. The ST isogeometric discretization enables increased accuracy in the flow solution. With the MDM, a long wake can be computed over a sequence of subdomains, instead of a single, long domain, thus somewhat reducing the computational cost. Furthermore, with the MDM, the computation over a downstream subdomain can start several turbine rotations after the computation over the upstream subdomain starts, thus reducing the computational cost even more. All these good features of the framework, in combination, enable accurate representation of the turbine long-wake vortex patterns in a computationally efficient way. In the computations we present, the velocity data on the inflow plane comes from a previous wind turbine computation, extracted by projection from a plane located 10 m downstream of the turbine, which has a diameter of 126 m. The results show the effectiveness of the framework in wind turbine long-wake computation.

[106]

L. Aydinbakar, K. Takizawa, T.E. Tezduyar, and T. Kuraishi, “Space–time VMS isogeometric analysis of the Taylor–Couette flow”, Computational Mechanics, 67 (2021) 1515–1541, 10.1007/s00466-021-02004-6
Times Cited in Web of Science Core Collection: 19, Times Cited in Scopus: 24
@ARTICLE{Aydinbakar21a, AUTHOR = {L.~Aydinbakar and K.~Takizawa and T. E.~Tezduyar and T.~Kuraishi}, JOURNAL = {Computational Mechanics}, TITLE = {Space–Time {VMS} Isogeometric Analysis of the {T}aylor–{C}ouette Flow}, VOLUME = {67}, YEAR = {2021}, PAGES = {1515–1541}, DOI = {10.1007/s00466-021-02004-6} } Abstract:
The Taylor–Couette flow is a classical fluid mechanics problem that exhibits, depending on the Reynolds number, a range of flow patterns, with the interesting ones having small-scale structures, and sometimes even wavy nature. Accurate representation of these flow patterns in computational flow analysis requires methods that can, with a reasonable computational cost, represent the circular geometry accurately and provide a high-fidelity flow solution. We use the Space–Time Variational Multiscale (ST-VMS) method with ST isogeometric discretization to address these computational challenges and to evaluate how the method and discretization perform under different scenarios of computing the Taylor–Couette flow. We conduct the computational analysis with different combinations of the Reynolds numbers based on the inner and outer cylinder rotation speeds, with different choices of the reference frame, one of which leads to rotating the mesh, with the full-domain and rotational-periodicity representations of the flow field, with both the convective and conservative forms of the ST-VMS, with both the strong and weak enforcement of the prescribed velocities on the cylinder surfaces, and with different mesh refinements. The ST framework provides higher-order accuracy in general, and the VMS feature of the ST-VMS addresses the computational challenges associated with the multiscale nature of the flow. The ST isogeometric discretization enables exact representation of the circular geometry and increased accuracy in the flow solution. In computations where the mesh is rotating, the ST/NURBS Mesh Update Method, with NURBS basis functions in time, enables exact representation of the mesh rotation, in terms of both the paths of the mesh points and the velocity of the points along their paths. In computations with rotational-periodicity representation of the flow field, the periodicity is enforced with the ST Slip Interface method. With the combinations of the Reynolds numbers used in the computations, we cover the cases leading to the Taylor vortex flow and the wavy vortex flow, where the waves are in motion. Our work shows that all these ST methods, integrated together, offer a high-fidelity computational analysis platform for the Taylor–Couette flow and for other classes of flow problems with similar features.

[105]

L. Aydinbakar, K. Takizawa, T.E. Tezduyar, and D. Matsuda, “U-duct turbulent-flow computation with the ST-VMS method and isogeometric discretization”, Computational Mechanics, 67 (2021) 823–843, 10.1007/s00466-020-01965-4
Times Cited in Web of Science Core Collection: 19, Times Cited in Scopus: 24
@ARTICLE{Aydinbakar20a, AUTHOR = {L.~Aydinbakar and K.~Takizawa and T. E.~Tezduyar and D.~Matsuda}, JOURNAL = {Computational Mechanics}, TITLE = {U-duct turbulent-flow computation with the {ST-VMS} method and isogeometric discretization}, VOLUME = {67}, YEAR = {2021}, PAGES = {823–843}, DOI = {10.1007/s00466-020-01965-4} } Abstract:
The U-duct turbulent flow is a known benchmark problem with the computational challenges of high Reynolds number, high curvature and strong flow dependence on the inflow profile. We use this benchmark problem to test and evaluate the Space–Time Variational Multiscale (ST-VMS) method with ST isogeometric discretization. A fully-developed flow field in a straight duct with periodicity condition is used as the inflow profile. The ST-VMS serves as the core method. The ST framework provides higher-order accuracy in general, and the VMS feature of the ST-VMS addresses the computational challenges associated with the multiscale nature of the unsteady flow. The ST isogeometric discretization enables more accurate representation of the duct geometry and increased accuracy in the flow solution. In the straight-duct computations to obtain the inflow velocity, the periodicity condition is enforced with the ST Slip Interface method. All computations are carried out with quadratic NURBS meshes, which represent the circular arc of the duct exactly in the U-duct computations. We investigate how the results vary with the time-averaging range used in reporting the results, mesh refinement, and the Courant number. The results are compared to experimental data, showing that the ST-VMS with ST isogeometric discretization provides good accuracy in this class of flow problems.

[104]

P. Tonon, R.A.K. Sanches, K. Takizawa, and T.E. Tezduyar, “A linear-elasticity-based mesh moving method with no cycle-to-cycle accumulated distortion”, Computational Mechanics, 67 (2021) 413–434, 10.1007/s00466-020-01941-y
Times Cited in Web of Science Core Collection: 15, Times Cited in Scopus: 19
@ARTICLE{Tonon20a, AUTHOR = {P.~Tonon and R. A. K.~Sanches and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {A linear-elasticity-based mesh moving method with no cycle-to-cycle accumulated distortion}, VOLUME = {67}, YEAR = {2021}, PAGES = {413–434}, DOI = {10.1007/s00466-020-01941-y} } Abstract:
Good mesh moving methods are always part of what makes moving-mesh methods good in computation of flow problems with moving boundaries and interfaces, including fluid–structure interaction. Moving-mesh methods, such as the space–time (ST) and arbitrary Lagrangian–Eulerian (ALE) methods, enable mesh-resolution control near solid surfaces and thus high-resolution representation of the boundary layers. Mesh moving based on linear elasticity and mesh-Jacobian-based stiffening (MJBS) has been in use with the ST and ALE methods since 1992. In the MJBS, the objective is to stiffen the smaller elements, which are typically placed near solid surfaces, more than the larger ones, and this is accomplished by altering the way we account for the Jacobian of the transformation from the element domain to the physical domain. In computing the mesh motion between time levels tn and tn+1 with the linear-elasticity equations, the most common option is to compute the displacement from the configuration at tn. While this option works well for most problems, because the method is path-dependent, it involves cycle-to-cycle accumulated mesh distortion. The back-cycle-based mesh moving (BCBMM) method, introduced recently with two versions, can remedy that. In the BCBMM, there is no cycle-to-cycle accumulated distortion. In this article, for the first time, we present mesh moving test computations with the BCBMM. We also introduce a version we call “half-cycle-based mesh moving” (HCBMM) method, and that is for computations where the boundary or interface motion in the second half of the cycle consists of just reversing the steps in the first half and we want the mesh to behave the same way. We present detailed 2D and 3D test computations with finite element meshes, using as the test case the mesh motion associated with wing pitching. The computations show that all versions of the BCBMM perform well, with no cycle-to-cycle accumulated distortion, and with the HCBMM, as the wing in the second half of the cycle just reverses its motion steps in the first half, the mesh behaves the same way.

[103]

Y. Bazilevs, K. Takizawa, M.C.H. Wu, T. Kuraishi, R. Avsar, Z. Xu, and T.E. Tezduyar, “Gas turbine computational flow and structure analysis with isogeometric discretization and a complex-geometry mesh generation method”, Computational Mechanics, 67 (2021) 57–84, 10.1007/s00466-020-01919-w
Times Cited in Web of Science Core Collection: 41, Times Cited in Scopus: 49
@ARTICLE{Bazilevs20b, AUTHOR = {Y.~Bazilevs and K.~Takizawa and M. C. H.~Wu and T.~Kuraishi and R.~Avsar and Z.~Xu and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Gas turbine computational flow and structure analysis with isogeometric discretization and a complex-geometry mesh generation method}, VOLUME = {67}, YEAR = {2021}, PAGES = {57–84}, DOI = {10.1007/s00466-020-01919-w} } Abstract:
A recently introduced NURBS mesh generation method for complex-geometry Isogeometric Analysis (IGA) is applied to building a high-quality mesh for a gas turbine. The compressible flow in the turbine is computed using the IGA and a stabilized method with improved discontinuity-capturing, weakly-enforced no-slip boundary-condition, and sliding-interface operators. The IGA results are compared with the results from the stabilized finite element simulation to reveal superior performance of the NURBS-based approach. Free-vibration analysis of the turbine rotor using the structural mechanics NURBS mesh is also carried out and shows that the NURBS mesh generation method can be used also in structural mechanics analysis. With the flow field from the NURBS-based turbine flow simulation, the Courant number is computed based on the NURBS mesh local length scale in the flow direction to show some of the other positive features of the mesh generation framework. The work presented further advances the IGA as a fully-integrated and robust design-to-analysis framework, and the IGA-based complex-geometry flow computation with moving boundaries and interfaces represents the first of its kind for compressible flows.

[102]

Y. Otoguro, H. Mochizuki, K. Takizawa, and T.E. Tezduyar, “Space–time variational multiscale isogeometric analysis of a tsunami-shelter vertical-axis wind turbine”, Computational Mechanics, 66 (2020) 1443–1460, 10.1007/s00466-020-01910-5
Times Cited in Web of Science Core Collection: 33, Times Cited in Scopus: 40
@ARTICLE{Otoguro19b, AUTHOR = {Y.~Otoguro and H.~Mochizuki and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Space–Time Variational Multiscale Isogeometric Analysis of a tsunami-shelter vertical-axis wind turbine}, VOLUME = {66}, YEAR = {2020}, PAGES = {1443–1460}, DOI = {10.1007/s00466-020-01910-5} } Abstract:
We present computational flow analysis of a vertical-axis wind turbine (VAWT) that has been proposed to also serve as a tsunami shelter. In addition to the three-blade rotor, the turbine has four support columns at the periphery. The columns support the turbine rotor and the shelter. Computational challenges encountered in flow analysis of wind turbines in general include accurate representation of the turbine geometry, multiscale unsteady flow, and moving-boundary flow associated with the rotor motion. The tsunami-shelter VAWT, because of its rather high geometric complexity, poses the additional challenge of reaching high accuracy in turbine-geometry representation and flow solution when the geometry is so complex. We address the challenges with a space–time (ST) computational method that integrates three special ST methods around the core, ST Variational Multiscale (ST-VMS) method, and mesh generation and improvement methods. The three special methods are the ST Slip Interface (ST-SI) method, ST Isogeometric Analysis (ST-IGA), and the ST/NURBS Mesh Update Method (STNMUM). The ST-discretization feature of the integrated method provides higher-order accuracy compared to standard discretization methods. The VMS feature addresses the computational challenges associated with the multiscale nature of the unsteady flow. The moving-mesh feature of the ST framework enables high-resolution computation near the blades. The ST-SI enables moving-mesh computation of the spinning rotor. The mesh covering the rotor spins with it, and the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. The ST-IGA enables more accurate representation of the blade and other turbine geometries and increased accuracy in the flow solution. The STNMUM enables exact representation of the mesh rotation. A general-purpose NURBS mesh generation method makes it easier to deal with the complex turbine geometry. The quality of the mesh generated with this method is improved with a mesh relaxation method based on fiber-reinforced hyperelasticity and optimized zero-stress state. We present computations for the 2D and 3D cases. The computations show the effectiveness of our ST and mesh generation and relaxation methods in flow analysis of the tsunami-shelter VAWT.

[101]

Y. Ueda, Y. Otoguro, K. Takizawa, and T.E. Tezduyar, “Element-splitting-invariant local-length-scale calculation in B-spline meshes for complex geometries”, Mathematical Models and Methods in Applied Sciences, 30 (2020) 2139–2174, 10.1142/S0218202520500402
Times Cited in Web of Science Core Collection: 18, Times Cited in Scopus: 21
@ARTICLE{Ueda20a, AUTHOR = {Y.~Ueda and Y.~Otoguro and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Element-Splitting-Invariant Local-Length-Scale Calculation in {B}-Spline Meshes for Complex Geometries}, VOLUME = {30}, NUMBER = {None}, YEAR = {2020}, PAGES = {2139–2174}, DOI = {10.1142/S0218202520500402} } Abstract:
Variational multiscale methods and their precursors, stabilized methods, which are sometimes supplemented with discontinuity-capturing (DC) methods, have been playing their core-method role in flow computations increasingly with isogeometric discretization. The stabilization and DC parameters embedded in most of these methods play a significant role. The parameters almost always involve some local-length-scale expressions, most of the time in specific directions, such as the direction of the flow or solution gradient. Until recently, local-length-scale expressions originally intended for finite element discretization were being used also for isogeometric discretization. The direction-dependent expressions introduced in [Y. Otoguro, K. Takizawa and T. E. Tezduyar, Element length calculation in B-spline meshes for complex geometries, Comput. Mech. 65 (2020) 1085-1103, https://doi.org/10.1007/s00466-019-01809-w] target B-spline meshes for complex geometries. The key stages of deriving these expressions are mapping the direction vector from the physical element to the parent element in the parametric space, accounting for the discretization spacing along each of the parametric coordinates, and mapping what has been obtained back to the physical element. The expressions are based on a preferred parametric space and a transformation tensor that represents the relationship between the integration and preferred parametric spaces. Element splitting may be a part of the computational method in a variety of cases, including computations with T-spline discretization and immersed boundary and extended finite element methods and their isogeometric versions. We do not want the element splitting to influence the actual discretization, which is represented by the control or nodal points. Therefore, the local length scale should be invariant with respect to element splitting. In element definition, invariance of the local length scale is a crucial requirement, because, unlike the element definition choices based on implementation convenience or computational efficiency, it influences the solution. We provide a proof, in the context of B-spline meshes, for the element-splitting invariance of the local-length-scale expressions introduced in the above reference.

[100]

K. Takizawa, T.E. Tezduyar, and R. Avsar, “A low-distortion mesh moving method based on fiber-reinforced hyperelasticity and optimized zero-stress state”, Computational Mechanics, 65 (2020) 1567–1591, 10.1007/s00466-020-01835-z
Times Cited in Web of Science Core Collection: 23, Times Cited in Scopus: 30
@ARTICLE{Takizawa20b, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and R.~Avsar}, JOURNAL = {Computational Mechanics}, TITLE = {A Low-Distortion Mesh Moving Method Based on Fiber-Reinforced Hyperelasticity and Optimized Zero-Stress State}, VOLUME = {65}, YEAR = {2020}, PAGES = {1567–1591}, DOI = {10.1007/s00466-020-01835-z} } Abstract:
In computation of flow problems with moving boundaries and interfaces, including fluid–structure interaction, moving-mesh methods enable mesh-resolution control near the interface and consequently high-resolution representation of the boundary layers. Good moving-mesh methods require good mesh moving methods. We introduce a low-distortion mesh moving method based on fiber-reinforced hyperelasticity and optimized zero-stress state (ZSS). The method has been developed targeting isogeometric discretization but is also applicable to finite element discretization. With the large-deformation mechanics equations, we can expect to have a unique mesh associated with each step of the boundary or interface motion. With the fibers placed in multiple directions, we stiffen the element in those directions for the purpose of reducing the distortion during the mesh deformation. We optimize the ZSS by seeking orthogonality of the parametric directions, by mesh relaxation, and by making the ZSS time-dependent as needed. We present 2D and 3D test computations with isogeometric discretization. The computations show that the mesh moving method introduced performs well.

[99]

A. Castorrini, P. Venturini, A. Corsini, F. Rispoli, K. Takizawa, and T.E. Tezduyar, “Computational analysis of particle-laden-airflow erosion and experimental verification”, Computational Mechanics, 65 (2020) 1549–1565, 10.1007/s00466-020-01834-0
Times Cited in Web of Science Core Collection: 10, Times Cited in Scopus: 14
@ARTICLE{Castorrini20a, AUTHOR = {A.~Castorrini and P.~Venturini and A.~Corsini and F.~Rispoli and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Computational Analysis of Particle-Laden-Airflow Erosion and Experimental Verification}, VOLUME = {65}, YEAR = {2020}, PAGES = {1549–1565}, DOI = {10.1007/s00466-020-01834-0} } Abstract:
Computational analysis of particle-laden-airflow erosion can help engineers have a better understanding of the erosion process, maintenance and protection of turbomachinery components. We present an integrated method for this class of computational analysis. The main components of the method are the residual-based Variational Multiscale (VMS) method, a finite element particle-cloud tracking (PCT) method with ellipsoidal clouds, an erosion model based on two time scales, and the Solid-Extension Mesh Moving Technique (SEMMT). The turbulent-flow nature of the analysis is addressed with the VMS, the particle-cloud trajectories are calculated based on the time-averaged computed flow field and closure models defined for the turbulent dispersion of particles, and one-way dependence is assumed between the flow and particle dynamics. Because the target-geometry update due to the erosion has a very long time scale compared to the fluid–particle dynamics, the update takes place in a sequence of “evolution steps” representing the impact of the erosion. A scale-up factor, calculated based on the update threshold criterion, relates the erosions and particle counts in the evolution steps to those in the PCT computation. As the target geometry evolves, the mesh is updated with the SEMMT. We present a computation designed to match the sand-erosion experiment we conducted with an aluminum-alloy target. We show that, despite the problem complexities and model assumptions involved, we have a reasonably good agreement between the computed and experimental data.

[98]

T. Terahara, K. Takizawa, T.E. Tezduyar, A. Tsushima, and K. Shiozaki, “Ventricle-valve-aorta flow analysis with the Space–Time Isogeometric Discretization and Topology Change”, Computational Mechanics, 65 (2020) 1343–1363, 10.1007/s00466-020-01822-4
Times Cited in Web of Science Core Collection: 53, Times Cited in Scopus: 58
@ARTICLE{Terahara19b, AUTHOR = {T.~Terahara and K.~Takizawa and T. E.~Tezduyar and A.~Tsushima and K.~Shiozaki}, JOURNAL = {Computational Mechanics}, TITLE = {Ventricle-valve-aorta flow analysis with the {S}pace–{T}ime {I}sogeometric {D}iscretization and {T}opology {C}hange}, VOLUME = {65}, YEAR = {2020}, PAGES = {1343–1363}, DOI = {10.1007/s00466-020-01822-4} } Abstract:
We address the computational challenges of and presents results from ventricle-valve-aorta flow analysis. Including the left ventricle (LV) in the model makes the flow into the valve, and consequently the flow into the aorta, anatomically more realistic. The challenges include accurate representation of the boundary layers near moving solid surfaces even when the valve leaflets come into contact, computation with high geometric complexity, anatomically realistic representation of the LV motion, and flow stability at the inflow boundary, which has a traction condition. The challenges are mainly addressed with a Space–Time (ST) method that integrates three special ST methods around the core, ST Variational Multiscale (ST-VMS) method. The three special methods are the ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods and ST Isogeometric Analysis (ST-IGA). The ST-discretization feature of the integrated method, ST-SI-TC-IGA, provides higher-order accuracy compared to standard discretization methods. The VMS feature addresses the computational challenges associated with the multiscale nature of the unsteady flow in the LV, valve and aorta. The moving-mesh feature of the ST framework enables high-resolution computation near the leaflets. The ST-TC enables moving-mesh computation even with the TC created by the contact between the leaflets, dealing with the contact while maintaining high-resolution representation near the leaflets. The ST-IGA provides smoother representation of the LV, valve and aorta surfaces and increased accuracy in the flow solution. The ST-SI connects the separately generated LV, valve and aorta NURBS meshes, enabling easier mesh generation, connects the mesh zones containing the leaflets, enabling a more effective mesh moving, helps the ST-TC deal with leaflet–leaflet contact location change and contact sliding, and helps the ST-TC and ST-IGA keep the element density in the narrow spaces near the contact areas at a reasonable level. The ST-SI-TC-IGA is supplemented with two other special methods in this article. A structural mechanics computation method generates the LV motion from the CT scans of the LV and anatomically realistic values for the LV volume ratio. The Constrained-Flow-Profile (CFP) Traction provides flow stability at the inflow boundary. Test computation with the CFP Traction shows its effectiveness as an inflow stabilization method, and computation with the LV-valve-aorta model shows the effectiveness of the ST-SI-TC-IGA and the two supplemental methods.

[97]

T. Terahara, K. Takizawa, T.E. Tezduyar, Y. Bazilevs, and M.-C. Hsu, “Heart valve isogeometric sequentially-coupled FSI analysis with the space–time topology change method”, Computational Mechanics, 65 (2020) 1167–1187, 10.1007/s00466-019-01813-0
Times Cited in Web of Science Core Collection: 58, Times Cited in Scopus: 70
@ARTICLE{Terahara19a, AUTHOR = {T.~Terahara and K.~Takizawa and T. E.~Tezduyar and Y.~Bazilevs and Ming-Chen Hsu}, JOURNAL = {Computational Mechanics}, TITLE = {Heart Valve Isogeometric Sequentially-Coupled {FSI} Analysis with the Space–Time Topology Change Method}, VOLUME = {65}, YEAR = {2020}, PAGES = {1167–1187}, DOI = {10.1007/s00466-019-01813-0} } Abstract:
Heart valve fluid–structure interaction (FSI) analysis is one of the computationally challenging cases in cardiovascular fluid mechanics. The challenges include unsteady flow through a complex geometry, solid surfaces with large motion, and contact between the valve leaflets. We introduce here an isogeometric sequentially-coupled FSI (SCFSI) method that can address the challenges with an outcome of high-fidelity flow solutions. The SCFSI analysis enables dealing with the fluid and structure parts individually at different steps of the solutions sequence, and also enables using different methods or different mesh resolution levels at different steps. In the isogeometric SCFSI analysis here, the first step is a previously computed (fully) coupled Immersogeometric Analysis FSI of the heart valve with a reasonable flow solution. With the valve leaflet and arterial surface motion coming from that, we perform a new, higher-fidelity fluid mechanics computation with the space–time topology change method and isogeometric discretization. Both the immersogeometric and space–time methods are variational multiscale methods. The computation presented for a bioprosthetic heart valve demonstrates the power of the method introduced.

[96]

Y. Otoguro, K. Takizawa, and T.E. Tezduyar, “Element length calculation in B-spline meshes for complex geometries”, Computational Mechanics, 65 (2020) 1085–1103, 10.1007/s00466-019-01809-w
Times Cited in Web of Science Core Collection: 31, Times Cited in Scopus: 36
@ARTICLE{Otoguro19c, AUTHOR = {Y.~Otoguro and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Element Length Calculation in {B}-Spline meshes for Complex Geometries}, VOLUME = {65}, YEAR = {2020}, PAGES = {1085–1103}, DOI = {10.1007/s00466-019-01809-w} } Abstract:
Variational multiscale methods, and their precursors, stabilized methods, have been playing a core-method role in semi-discrete and space–time (ST) flow computations for decades. These methods are sometimes supplemented with discontinuity-capturing (DC) methods. The stabilization and DC parameters embedded in most of these methods play a significant role. Various well-performing stabilization and DC parameters have been introduced in both the semi-discrete and ST contexts. The parameters almost always involve some element length expressions, most of the time in specific directions, such as the direction of the flow or solution gradient. Until recently, stabilization and DC parameters originally intended for finite element discretization were being used also for isogeometric discretization. Recently, element lengths and stabilization and DC parameters targeting isogeometric discretization were introduced for ST and semi-discrete computations, and these expressions are also applicable to finite element discretization. The key stages of deriving the direction-dependent element length expression were mapping the direction vector from the physical (ST or space-only) element to the parent element in the parametric space, accounting for the discretization spacing along each of the parametric coordinates, and mapping what has been obtained back to the physical element. Targeting B-spline meshes for complex geometries, we introduce here new element length expressions, which are outcome of a clear and convincing derivation and more suitable for element-level evaluation. The new expressions are based on a preferred parametric space and a transformation tensor that represents the relationship between the integration and preferred parametric spaces. The test computations we present for advection-dominated cases, including 2D computations with complex meshes, show that the proposed element length expressions result in good solution profiles.

[95]

K. Takizawa, Y. Ueda, and T.E. Tezduyar, “A node-numbering-invariant directional length scale for simplex elements”, Mathematical Models and Methods in Applied Sciences, 29 (2019) 2719–2753, 10.1142/S0218202519500581
Times Cited in Web of Science Core Collection: 27, Times Cited in Scopus: 31
@ARTICLE{Takizawa19b, AUTHOR = {K.~Takizawa and Y.~Ueda and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {A Node-Numbering-Invariant Directional Length Scale for Simplex Elements}, VOLUME = {29}, NUMBER = {None}, YEAR = {2019}, PAGES = {2719–2753}, DOI = {10.1142/S0218202519500581} } Abstract:
Variational multiscale methods, and their precursors, stabilized methods, have been very popular in flow computations in the past several decades. Stabilization parameters embedded in most of these methods play a significant role. The parameters almost always involve element length scales, most of the time in specific directions, such as the direction of the flow or solution gradient. We require the length scales, including the directional length scales, to have node-numbering invariance for all element types, including simplex elements. We propose a length scale expression meeting that requirement. We analytically evaluate the expression in the context of simplex elements and compared to one of the most widely used length scale expressions and show the levels of noninvariance avoided.

[94]

Y. Yu, Y.J. Zhang, K. Takizawa, T.E. Tezduyar, and T. Sasaki, “Anatomically realistic lumen motion representation in patient-specific space–time isogeometric flow analysis of coronary arteries with time-dependent medical-image data”, Computational Mechanics, 65 (2020) 395–404, 10.1007/s00466-019-01774-4
Times Cited in Web of Science Core Collection: 34, Times Cited in Scopus: 39
@ARTICLE{YuYuxuan19a, AUTHOR = {Y.~Yu and Y. J.~Zhang and K.~Takizawa and T. E.~Tezduyar and T.~Sasaki}, JOURNAL = {Computational Mechanics}, TITLE = {Anatomically Realistic Lumen Motion Representation in Patient-Specific Space–Time Isogeometric Flow Analysis of Coronary Arteries with Time-Dependent Medical-Image Data}, VOLUME = {65}, YEAR = {2020}, PAGES = {395–404}, DOI = {10.1007/s00466-019-01774-4} } Abstract:
Patient-specific computational flow analysis of coronary arteries with time-dependent medical-image data can provide valuable information to doctors making treatment decisions. Reliable computational analysis requires a good core method, high-fidelity space and time discretizations, and an anatomically realistic representation of the lumen motion. The space–time variational multiscale (ST-VMS) method has a good track record as a core method. The ST framework, in a general context, provides higher-order accuracy. The VMS feature of the ST-VMS addresses the computational challenges associated with the multiscale nature of the unsteady flow in the artery. The moving-mesh feature of the ST framework enables high-resolution flow computation near the moving fluid–solid interfaces. The ST isogeometric analysis is a superior discretization method. With IGA basis functions in space, it enables more accurate representation of the lumen geometry and increased accuracy in the flow solution. With IGA basis functions in time, it enables a smoother representation of the lumen motion and a mesh motion consistent with that. With cubic NURBS in time, we obtain a continuous acceleration from the lumen-motion representation. Here we focus on making the lumen-motion representation anatomically realistic. We present a method to obtain from medical-image data in discrete form an anatomically realistic NURBS representation of the lumen motion, without sudden, unrealistic changes introduced by the higher-order representation. In the discrete projection from the medical-image data to the NURBS representation, we supplement the least-squares terms with two penalty terms, corresponding to the first and second time derivatives of the control-point trajectories. The penalty terms help us avoid the sudden unrealistic changes. The computation we present demonstrates the effectiveness of the method.

[93]

T. Kuraishi, K. Takizawa, and T.E. Tezduyar, “Space–time computational analysis of tire aerodynamics with actual geometry, road contact, tire deformation, road roughness and fluid film”, Computational Mechanics, 64 (2019) 1699–1718, 10.1007/s00466-019-01746-8
Times Cited in Web of Science Core Collection: 38, Times Cited in Scopus: 48
@ARTICLE{Kuraishi19b, AUTHOR = {T.~Kuraishi and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Space–Time Computational Analysis of Tire Aerodynamics with Actual Geometry, Road Contact, Tire Deformation, Road Roughness and Fluid Film}, VOLUME = {64}, YEAR = {2019}, PAGES = {1699–1718}, DOI = {10.1007/s00466-019-01746-8} } Abstract:
The space–time (ST) computational method “ST-SI-TC-IGA” has recently enabled computational analysis of tire aerodynamics with actual tire geometry, road contact and tire deformation. The core component of the ST-SI-TC-IGA is the ST Variational Multiscale (ST-VMS) method, and the other key components are the ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods and the ST Isogeometric Analysis (ST-IGA). These ST methods played their parts in overcoming the computational challenges, including (i) the complexity of an actual tire geometry with longitudinal and transverse grooves, (ii) the spin of the tire, (iii) maintaining accurate representation of the boundary layers near the tire while being able to deal with the flow-domain topology change created by the road contact, and (iv) the turbulent nature of the flow. The combination of the ST-VMS, ST-SI and the ST-IGA has also recently enabled solution of fluid film problems with a computational cost comparable to that of the Reynolds-equation model for the comparable solution quality. This was accomplished with the computational flexibility to go beyond the limitations of the Reynolds-equation model. Here we include and address the computational challenges associated with the road roughness and the fluid film between the tire and the road. The new methods we add to accomplish that include a remedy for the trapped fluid, a method for reducing the number of control points as a space occupied by the fluid shrinks down to a narrow gap, and a method for representing the road roughness. We present computations for a 2D test problem with a straight channel, a simple 2D model of the tire, and a 3D model with actual tire geometry and road roughness. The computations show the effectiveness of our integrated set of ST methods targeting tire aerodynamics.

[92]

Y. Otoguro, K. Takizawa, T.E. Tezduyar, K. Nagaoka, R. Avsar, and Y. Zhang, “Space–time VMS flow analysis of a turbocharger turbine with isogeometric discretization: computations with time-dependent and steady-inflow representations of the intake/exhaust cycle”, Computational Mechanics, 64 (2019) 1403–1419, 10.1007/s00466-019-01722-2
Times Cited in Web of Science Core Collection: 47, Times Cited in Scopus: 52
@ARTICLE{Otoguro19a, AUTHOR = {Y.~Otoguro and K.~Takizawa and T. E.~Tezduyar and K.~Nagaoka and R.~Avsar and Y.~Zhang}, JOURNAL = {Computational Mechanics}, TITLE = {Space–Time {VMS} Flow Analysis of a Turbocharger Turbine with Isogeometric Discretization: Computations with Time-Dependent and Steady-Inflow Representations of the Intake/Exhaust Cycle}, VOLUME = {64}, YEAR = {2019}, PAGES = {1403–1419}, DOI = {10.1007/s00466-019-01722-2} } Abstract:
Many of the computational challenges encountered in turbocharger-turbine flow analysis have been addressed by an integrated set of space–time (ST) computational methods. The core computational method is the ST variational multiscale (ST-VMS) method. The ST framework provides higher-order accuracy in general, and the VMS feature of the ST-VMS addresses the computational challenges associated with the multiscale nature of the unsteady flow. The moving-mesh feature of the ST framework enables high-resolution computation near the rotor surface. The ST slip interface (ST-SI) method enables moving-mesh computation of the spinning rotor. The mesh covering the rotor spins with it, and the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. The ST Isogeometric Analysis enables more accurate representation of the turbine geometry and increased accuracy in the flow solution. The ST/NURBS Mesh Update Method enables exact representation of the mesh rotation. A general-purpose NURBS mesh generation method makes it easier to deal with the complex geometries involved. An SI also provides mesh generation flexibility in a general context by accurately connecting the two sides of the solution computed over nonmatching meshes, and that is enabling the use of nonmatching NURBS meshes in the computations. The computational analysis needs to cover a full intake/exhaust cycle, which is much longer than the turbine rotation cycle because of high rotation speeds, and the long duration required is an additional computational challenge. As one way of addressing that challenge, we propose here to calculate the turbine efficiency for the intake/exhaust cycle by interpolation from the efficiencies associated with a set of steady-inflow computations at different flow rates. The efficiencies obtained from the computations with time-dependent and steady-inflow representations of the intake/exhaust cycle compare well. This demonstrates that predicting the turbine performance from a set of steady-inflow computations is a good way of addressing the challenge associated with the multiple time scales.

[91]

A. Castorrini, A. Corsini, F. Rispoli, P. Venturini, K. Takizawa, and T.E. Tezduyar, “Computational analysis of performance deterioration of a wind turbine blade strip subjected to environmental erosion”, Computational Mechanics, 64 (2019) 1133–1153, 10.1007/s00466-019-01697-0
Times Cited in Web of Science Core Collection: 36, Times Cited in Scopus: 44
@ARTICLE{Castorrini19b, AUTHOR = {A.~Castorrini and A.~Corsini and F.~Rispoli and P.~Venturini and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Computational analysis of performance deterioration of a wind turbine blade strip subjected to environmental erosion}, VOLUME = {64}, YEAR = {2019}, PAGES = {1133–1153}, DOI = {10.1007/s00466-019-01697-0} } Abstract:
Wind-turbine blade rain and sand erosion, over long periods of time, can degrade the aerodynamic performance and therefore the power production. Computational analysis of the erosion can help engineers have a better understanding of the maintenance and protection requirements. We present an integrated method for this class of computational analysis. The main components of the method are the streamline-upwind/Petrov–Galerkin (SUPG) and pressure-stabilizing/Petrov–Galerkin (PSPG) stabilizations, a finite element particle-cloud tracking method, an erosion model based on two time scales, and the solid-extension mesh moving technique (SEMMT). The turbulent-flow nature of the analysis is handled with a Reynolds-averaged Navier–Stokes model and SUPG/PSPG stabilization, the particle-cloud trajectories are calculated based on the computed flow field and closure models defined for the turbulent dispersion of particles, and one-way dependence is assumed between the flow and particle dynamics. Because the geometry update due to the erosion has a very long time scale compared to the fluid–particle dynamics, the update takes place in a sequence of “evolution steps” representing the impact of the erosion. A scale-up factor, calculated in different ways depending on the update threshold criterion, relates the erosions and particle counts in the evolution steps to those in the fluid–particle simulation. As the blade geometry evolves, the mesh is updated with the SEMMT. We present computational analysis of rain and sand erosion for a wind-turbine blade strip, including a case with actual rainfall data and experimental aerodynamic data for eroded airfoil geometries.

[90]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Computational analysis methods for complex unsteady flow problems”, Mathematical Models and Methods in Applied Sciences, 29 (2019) 825–838, 10.1142/S0218202519020020
Times Cited in Web of Science Core Collection: 25, Times Cited in Scopus: 28
@ARTICLE{Bazilevs19a, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Computational Analysis Methods for Complex Unsteady Flow Problems}, VOLUME = {29}, NUMBER = {None}, YEAR = {2019}, PAGES = {825–838}, DOI = {10.1142/S0218202519020020} } Abstract:
In this lead paper of the special issue, we provide a brief summary of the stabilized and multiscale methods in fluid dynamics. We highlight the key features of the stabilized and multiscale scale methods, and variational methods in general, that make these approaches well suited for computational analysis of complex, unsteady flows encountered in modern science and engineering applications. We mainly focus on the recent developments. We discuss application of the variational multiscale (VMS) methods to fluid dynamics problems involving computational challenges associated with high-Reynolds-number flows, wall-bounded turbulent flows, flows on moving domains including subdomains in relative motion, fluid-structure interaction (FSI), and complex-fluid flows with FSI.

[89]

T. Sasaki, K. Takizawa, and T.E. Tezduyar, “Medical-image-based aorta modeling with zero-stress-state estimation”, Computational Mechanics, 64 (2019) 249–271, 10.1007/s00466-019-01669-4
Times Cited in Web of Science Core Collection: 32, Times Cited in Scopus: 39
@ARTICLE{Sasaki19a, AUTHOR = {T.~Sasaki and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Medical-Image-Based Aorta Modeling with Zero-Stress-State Estimation}, VOLUME = {64}, YEAR = {2019}, PAGES = {249–271}, DOI = {10.1007/s00466-019-01669-4} } Abstract:
Because the medical-image-based geometries used in patient-specific arterial fluid–structure interaction computations do not come from the zero-stress state (ZSS) of the artery, we need to estimate the ZSS required in the computations. The task becomes even more challenging for arteries with complex geometries, such as the aorta. In a method we introduced earlier the estimate is based on T-spline discretization of the arterial wall and is in the form of integration-point-based ZSS (IPBZSS). The T-spline discretization enables dealing with complex arterial geometries, such as an aorta model with branches, while retaining the desirable features of isogeometric discretization. With higher-order basis functions of the isogeometric discretization, we may be able to achieve a similar level of accuracy as with the linear basis functions, but using larger-size and fewer elements. In addition, the higher-order basis functions allow representation of more complex shapes within an element. The IPBZSS is a convenient representation of the ZSS because with isogeometric discretization, especially with T-spline discretization, specifying conditions at integration points is more straightforward than imposing conditions on control points. The method has two main components. 1. An iteration technique, which starts with a calculated ZSS initial guess, is used for computing the IPBZSS such that when a given pressure load is applied, the medical-image-based target shape is matched. 2. A design procedure, which is based on the Kirchhoff–Love shell model of the artery, is used for calculating the ZSS initial guess. Here we increase the scope and robustness of the method by introducing a new design procedure for the ZSS initial guess. The new design procedure has two features. (a) An IPB shell-like coordinate system, which increases the scope of the design to general parametrization in the computational space. (b) Analytical solution of the force equilibrium in the normal direction, based on the Kirchhoff–Love shell model, which places proper constraints on the design parameters. This increases the estimation accuracy, which in turn increases the robustness of the iterations and the convergence speed. To show how the new design procedure for the ZSS initial guess performs, we first present 3D test computations with a straight tube and a Y-shaped tube. Then we present a 3D computation where the target geometry is coming from medical image of a human aorta, and we include the branches in the model.

[88]

A. Castorrini, A. Corsini, F. Rispoli, K. Takizawa, and T.E. Tezduyar, “A stabilized ALE method for computational fluid–structure interaction analysis of passive morphing in turbomachinery”, Mathematical Models and Methods in Applied Sciences, 29 (2019) 967–994, 10.1142/S0218202519410057
Times Cited in Web of Science Core Collection: 30, Times Cited in Scopus: 41
@ARTICLE{Castorrini19a, AUTHOR = {A.~Castorrini and A.~Corsini and F.~Rispoli and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {A stabilized {ALE} method for computational fluid–structure interaction analysis of passive morphing in turbomachinery}, VOLUME = {29}, NUMBER = {None}, YEAR = {2019}, PAGES = {967–994}, DOI = {10.1142/S0218202519410057} } Abstract:
Computational fluid-structure interaction (FSI) and flow analysis now have a significant role in design and performance evaluation of turbomachinery systems, such as wind turbines, fans, and turbochargers. With increasing scope and fidelity, computational analysis can help improve the design and performance. For example, it can help add a passive morphing attachment (MA) to the blades of an axial fan for the purpose of controlling the blade load and section stall. We present a stabilized Arbitrary Lagrangian-Eulerian (ALE) method for computational FSI analysis of passive morphing in turbomachinery. The main components of the method are the Streamline-Upwind/Petrov-Galerkin (SUPG) and Pressure-Stabilizing/Petrov-Galerkin (PSPG) stabilizations in the ALE framework, mesh moving with Jacobian-based stiffening, and block-iterative FSI coupling. The turbulent-flow nature of the analysis is handled with a Reynolds-Averaged Navier-Stokes (RANS) model and SUPG/PSPG stabilization, supplemented with the “DRDJ” stabilization. As the structure moves, the fluid mechanics mesh moves with the Jacobian-based stiffening method, which reduces the deformation of the smaller elements placed near the solid surfaces. The FSI coupling between the blocks of the fully-discretized equation system representing the fluid mechanics, structural mechanics, and mesh moving equations is handled with the block-iterative coupling method. We present two-dimensional (2D) and three-dimensional (3D) computational FSI studies for an MA added to an axial-fan blade. The results from the 2D study are used in determining the spanwise length of the MA in the 3D study.

[87]

T. Kuraishi, K. Takizawa, and T.E. Tezduyar, “Space–Time Isogeometric flow analysis with built-in Reynolds-equation limit”, Mathematical Models and Methods in Applied Sciences, 29 (2019) 871–904, 10.1142/S0218202519410021
Times Cited in Web of Science Core Collection: 35, Times Cited in Scopus: 42
@ARTICLE{Kuraishi19a, AUTHOR = {T.~Kuraishi and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {{S}pace–{T}ime {I}sogeometric Flow Analysis with Built-in {R}eynolds-Equation Limit}, VOLUME = {29}, NUMBER = {None}, YEAR = {2019}, PAGES = {871–904}, DOI = {10.1142/S0218202519410021} } Abstract:
We present a space-time (ST) computational flow analysis method with built-in Reynolds-equation limit. The method enables solution of lubrication fluid dynamics problems with a computational cost comparable to that of the Reynolds-equation model for the comparable solution quality, but with the computational flexibility to go beyond the limitations of the Reynolds-equation model. The key components of the method are the ST Variational Multiscale (ST-VMS) method, ST Isogeometric Analysis (ST-IGA), and the ST Slip Interface (ST-SI) method. The VMS feature of the ST-VMS serves as a numerical stabilization method with a good track record, the moving-mesh feature of the ST framework enables high-resolution flow computation near the moving fluid-solid interfaces, and the higher-order accuracy of the ST framework strengthens both features. The ST-IGA enables more accurate representation of the solid-surface geometries and increased accuracy in the flow solution in general. With the ST-IGA, even with just one quadratic NURBS element across the gap of the lubrication fluid dynamics problem, we reach a solution quality comparable to that of the Reynolds-equation model. The ST-SI enables moving-mesh computation when the spinning solid surface is noncircular. The mesh covering the solid surface spins with it, retaining the high-resolution representation of the flow near the surface, and the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. We present detailed 2D test computations to show how the method performs compared to the Reynolds-equation model, compared to finite element discretization, at different circumferential and normal mesh refinement levels, when there is an SI in the mesh, and when the no-slip boundary conditions are weakly-enforced.

[86]

T. Kanai, K. Takizawa, T.E. Tezduyar, K. Komiya, M. Kaneko, K. Hirota, M. Nohmi, T. Tsuneda, M. Kawai, and M. Isono, “Methods for computation of flow-driven string dynamics in a pump and residence time”, Mathematical Models and Methods in Applied Sciences, 29 (2019) 839–870, 10.1142/S021820251941001X
Times Cited in Web of Science Core Collection: 35, Times Cited in Scopus: 45
@ARTICLE{Kanai18b, AUTHOR = {T.~Kanai and K.~Takizawa and T. E.~Tezduyar and K.~Komiya and M.~Kaneko and K.~Hirota and M.~Nohmi and T.~Tsuneda and M.~Kawai and M.~Isono}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Methods for Computation of Flow-Driven String Dynamics in a Pump and Residence Time}, VOLUME = {29}, NUMBER = {None}, YEAR = {2019}, PAGES = {839–870}, DOI = {10.1142/S021820251941001X} } Abstract:
We present methods for computation of flow-driven string dynamics in a pump and related residence time. The string dynamics computations help us understand how the strings carried by a fluid interact with the pump surfaces, including the blades, and get stuck on or around those surfaces. The residence time computations help us to have a simplified but quick understanding of the string behavior. The core computational method is the Space-Time Variational Multiscale (ST-VMS) method, and the other key methods are the ST Isogeometric Analysis (ST-IGA), ST Slip Interface (ST-SI) method, ST/NURBS Mesh Update Method (STNMUM), a general-purpose NURBS mesh generation method for complex geometries, and a one-way-dependence model for the string dynamics. The ST-IGA with NURBS basis functions in space is used in both fluid mechanics and string structural dynamics. The ST framework provides higher-order accuracy. The VMS feature of the ST-VMS addresses the computational challenges associated with the turbulent nature of the unsteady flow, and the moving-mesh feature of the ST framework enables high-resolution computation near the rotor surface. The ST-SI enables moving-mesh computation of the spinning rotor. The mesh covering the rotor spins with it, and the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. The ST-IGA enables more accurate representation of the pump geometry and increased accuracy in the flow solution. The IGA discretization also enables increased accuracy in the structural dynamics solution, as well as smoothness in the string shape and fluid dynamics forces computed on the string. The STNMUM enables exact representation of the mesh rotation. The general-purpose NURBS mesh generation method makes it easier to deal with the complex geometry we have here. With the one-way-dependence model, we compute the influence of the flow on the string dynamics, while avoiding the formidable task of computing the influence of the string on the flow, which we expect to be small.

[85]

T. Sasaki, K. Takizawa, and T.E. Tezduyar, “Aorta zero-stress state modeling with T-spline discretization”, Computational Mechanics, 63 (2019) 1315–1331, 10.1007/s00466-018-1651-0
Times Cited in Web of Science Core Collection: 28, Times Cited in Scopus: 34
@ARTICLE{Sasaki18a, AUTHOR = {T.~Sasaki and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Aorta Zero-Stress State Modeling with {T}-Spline Discretization}, VOLUME = {63}, YEAR = {2019}, PAGES = {1315–1331}, DOI = {10.1007/s00466-018-1651-0} } Abstract:
The image-based arterial geometries used in patient-specific arterial fluid–structure interaction (FSI) computations, such as aorta FSI computations, do not come from the zero-stress state (ZSS) of the artery. We propose a method for estimating the ZSS required in the computations. Our estimate is based on T-spline discretization of the arterial wall and is in the form of integration-point-based ZSS (IPBZSS). The method has two main components. (1) An iterative method, which starts with a calculated initial guess, is used for computing the IPBZSS such that when a given pressure load is applied, the image-based target shape is matched. (2) A method, which is based on the shell model of the artery, is used for calculating the initial guess. The T-spline discretization enables dealing with complex arterial geometries, such as an aorta model with branches, while retaining the desirable features of isogeometric discretization. With higher-order basis functions of the isogeometric discretization, we may be able to achieve a similar level of accuracy as with the linear basis functions, but using larger-size and much fewer elements. In addition, the higher-order basis functions allow representation of more complex shapes within an element. The IPBZSS is a convenient representation of the ZSS because with isogeometric discretization, especially with T-spline discretization, specifying conditions at integration points is more straightforward than imposing conditions on control points. Calculating the initial guess based on the shell model of the artery results in a more realistic initial guess. To show how the new ZSS estimation method performs, we first present 3D test computations with a Y-shaped tube. Then we show a 3D computation where the target geometry is coming from medical image of a human aorta, and we include the branches in our model.

[84]

T. Kuraishi, K. Takizawa, and T.E. Tezduyar, “Tire aerodynamics with actual tire geometry, road contact and tire deformation”, Computational Mechanics, 63 (2019) 1165–1185, 10.1007/s00466-018-1642-1
Times Cited in Web of Science Core Collection: 55, Times Cited in Scopus: 64
@ARTICLE{Kuraishi18a, AUTHOR = {T.~Kuraishi and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Tire Aerodynamics with Actual Tire Geometry, Road Contact and Tire Deformation}, VOLUME = {63}, YEAR = {2019}, PAGES = {1165–1185}, DOI = {10.1007/s00466-018-1642-1} } Abstract:
Tire aerodynamics with actual tire geometry, road contact and tire deformation pose tough computational challenges. The challenges include (1) the complexity of an actual tire geometry with longitudinal and transverse grooves, (2) the spin of the tire, (3) maintaining accurate representation of the boundary layers near the tire while being able to deal with the flow-domain topology change created by the road contact and tire deformation, and (4) the turbulent nature of the flow. A new space–time (ST) computational method, “ST-SI-TC-IGA,” is enabling us to address these challenges. The core component of the ST-SI-TC-IGA is the ST Variational Multiscale (ST-VMS) method, and the other key components are the ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods and the ST Isogeometric Analysis (ST-IGA). The VMS feature of the ST-VMS addresses the challenge created by the turbulent nature of the flow, the moving-mesh feature of the ST framework enables high-resolution flow computation near the moving fluid–solid interfaces, and the higher-order accuracy of the ST framework strengthens both features. The ST-SI enables moving-mesh computation with the tire spinning. The mesh covering the tire spins with it, and the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. The ST-TC enables moving-mesh computation even with the TC created by the contact between the tire and the road. It deals with the contact while maintaining high-resolution flow representation near the tire. Integration of the ST-SI and ST-TC enables high-resolution representation even though parts of the SI are coinciding with the tire and road surfaces. It also enables dealing with the tire–road contact location change and contact sliding. By integrating the ST-IGA with the ST-SI and ST-TC, in addition to having a more accurate representation of the tire geometry and increased accuracy in the flow solution, the element density in the tire grooves and in the narrow spaces near the contact areas is kept at a reasonable level. We present computations with the ST-SI-TC-IGA and two models of flow around a rotating tire with road contact and prescribed deformation. One is a simple 2D model for verification purposes, and one is a 3D model with an actual tire geometry and a deformation pattern provided by the tire company. The computations show the effectiveness of the ST-SI-TC-IGA in tire aerodynamics.

[83]

A. Korobenko, Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Computer modeling of wind turbines: 1. ALE-VMS and ST-VMS aerodynamic and FSI analysis”, Archives of Computational Methods in Engineering, 26 (2019) 1059–1099, 10.1007/s11831-018-9292-1
Times Cited in Web of Science Core Collection: 40, Times Cited in Scopus: 51
@ARTICLE{Korobenko18b, AUTHOR = {A.~Korobenko and Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Archives of Computational Methods in Engineering}, TITLE = {Computer modeling of wind turbines: 1. {ALE-VMS} and {ST-VMS} aerodynamic and {FSI} analysis}, VOLUME = {26}, YEAR = {2019}, PAGES = {1059–1099}, DOI = {10.1007/s11831-018-9292-1} } Abstract:
This is the first part of a two-part article on computer modeling of wind turbines. We describe the recent advances made by our teams in ALE-VMS and ST-VMS computational aerodynamic and fluid–structure interaction (FSI) analysis of wind turbines. The ALE-VMS method is the variational multiscale version of the Arbitrary Lagrangian–Eulerian method. The VMS components are from the residual-based VMS method. The ST-VMS method is the VMS version of the Deforming-Spatial-Domain/Stabilized Space–Time method. The ALE-VMS and ST-VMS serve as the core methods in the computations. They are complemented by special methods that include the ALE-VMS versions for stratified flows, sliding interfaces and weak enforcement of Dirichlet boundary conditions, ST Slip Interface (ST-SI) method, NURBS-based isogeometric analysis, ST/NURBS Mesh Update Method (STNMUM), Kirchhoff–Love shell modeling of wind-turbine structures, and full FSI coupling. The VMS feature of the ALE-VMS and ST-VMS addresses the computational challenges associated with the multiscale nature of the unsteady flow, and the moving-mesh feature of the ALE and ST frameworks enables high-resolution computation near the rotor surface. The ST framework, in a general context, provides higher-order accuracy. The ALE-VMS version for sliding interfaces and the ST-SI enable moving-mesh computation of the spinning rotor. The mesh covering the rotor spins with it, and the sliding interface or the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. The ST-SI also enables prescribing the fluid velocity at the turbine rotor surface as weakly-enforced Dirichlet boundary condition. The STNMUM enables exact representation of the mesh rotation. The analysis cases reported include both the horizontal-axis and vertical-axis wind turbines, stratified and unstratified flows, standalone wind turbines, wind turbines with tower or support columns, aerodynamic interaction between two wind turbines, and the FSI between the aerodynamics and structural dynamics of wind turbines. Comparisons with experimental data are also included where applicable. The reported cases demonstrate the effectiveness of the ALE-VMS and ST-VMS computational analysis in wind-turbine aerodynamics and FSI.

[82]

T.E. Tezduyar and K. Takizawa, “Space–time computations in practical engineering applications: a summary of the 25-year history”, Computational Mechanics, 63 (2019) 747–753, 10.1007/s00466-018-1620-7
Times Cited in Web of Science Core Collection: 46, Times Cited in Scopus: 55
@ARTICLE{Tezduyar18a, AUTHOR = {T. E.~Tezduyar and K.~Takizawa}, JOURNAL = {Computational Mechanics}, TITLE = {Space–time computations in practical engineering applications: A summary of the 25-year history}, VOLUME = {63}, YEAR = {2019}, PAGES = {747–753}, DOI = {10.1007/s00466-018-1620-7} } Abstract:
In an article published online in July 2018 it was stated that the algorithm proposed in the article is “enabling practical implementation of the space–time FEM for engineering applications.” In fact, space–time computations in practical engineering applications were already enabled in 1993. We summarize the computations that have taken place since then. These computations started with finite element discretization and are now also with isogeometric discretization. They were all in 3D space and were all carried out on parallel computers. For quarter of a century, these computations brought solution to many classes of complex problems ranging from Orion spacecraft parachutes to wind turbines, from patient-specific cerebral aneurysms to heart valves, from thermo-fluid analysis of ground vehicles and tires to turbocharger turbines and exhaust manifolds.

[81]

K. Takizawa, T.E. Tezduyar, and T. Sasaki, “Isogeometric hyperelastic shell analysis with out-of-plane deformation mapping”, Computational Mechanics, 63 (2019) 681–700, 10.1007/s00466-018-1616-3
Times Cited in Web of Science Core Collection: 47, Times Cited in Scopus: 54
@ARTICLE{Takizawa18c, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Sasaki}, JOURNAL = {Computational Mechanics}, TITLE = {Isogeometric hyperelastic shell analysis with out-of-plane deformation mapping}, VOLUME = {63}, YEAR = {2019}, PAGES = {681–700}, DOI = {10.1007/s00466-018-1616-3} } Abstract:
We derive a hyperelastic shell formulation based on the Kirchhoff–Love shell theory and isogeometric discretization, where we take into account the out-of-plane deformation mapping. Accounting for that mapping affects the curvature term. It also affects the accuracy in calculating the deformed-configuration out-of-plane position, and consequently the nonlinear response of the material. In fluid–structure interaction analysis, when the fluid is inside a shell structure, the shell midsurface is what it would know. We also propose, as an alternative, shifting the “midsurface” location in the shell analysis to the inner surface, which is the surface that the fluid should really see. Furthermore, in performing the integrations over the undeformed configuration, we take into account the curvature effects, and consequently integration volume does not change as we shift the “midsurface” location. We present test computations with pressurized cylindrical and spherical shells, with Neo-Hookean and Fung’s models, for the compressible- and incompressible-material cases, and for two different locations of the “midsurface.” We also present test computation with a pressurized Y-shaped tube, intended to be a simplified artery model and serving as an example of cases with somewhat more complex geometry.

[80]

T. Kanai, K. Takizawa, T.E. Tezduyar, T. Tanaka, and A. Hartmann, “Compressible-flow geometric-porosity modeling and spacecraft parachute computation with isogeometric discretization”, Computational Mechanics, 63 (2019) 301–321, 10.1007/s00466-018-1595-4
Times Cited in Web of Science Core Collection: 64, Times Cited in Scopus: 77
@ARTICLE{Kanai18a, AUTHOR = {T.~Kanai and K.~Takizawa and T. E.~Tezduyar and T.~Tanaka and A.~Hartmann}, JOURNAL = {Computational Mechanics}, TITLE = {Compressible-Flow Geometric-Porosity Modeling and Spacecraft Parachute Computation with Isogeometric Discretization}, VOLUME = {63}, YEAR = {2019}, PAGES = {301–321}, DOI = {10.1007/s00466-018-1595-4} } Abstract:
One of the challenges in computational fluid–structure interaction (FSI) analysis of spacecraft parachutes is the “geometric porosity,” a design feature created by the hundreds of gaps and slits that the flow goes through. Because FSI analysis with resolved geometric porosity would be exceedingly time-consuming, accurate geometric-porosity modeling becomes essential. The geometric-porosity model introduced earlier in conjunction with the space–time FSI method enabled successful computational analysis and design studies of the Orion spacecraft parachutes in the incompressible-flow regime. Recently, porosity models and ST computational methods were introduced, in the context of finite element discretization, for compressible-flow aerodynamics of parachutes with geometric porosity. The key new component of the ST computational framework was the compressible-flow ST slip interface method, introduced in conjunction with the compressible-flow ST SUPG method. Here, we integrate these porosity models and ST computational methods with isogeometric discretization. We use quadratic NURBS basis functions in the computations reported. This gives us a parachute shape that is smoother than what we get from a typical finite element discretization. In the flow analysis, the combination of the ST framework, NURBS basis functions, and the SUPG stabilization assures superior computational accuracy. The computations we present for a drogue parachute show the effectiveness of the porosity models, ST computational methods, and the integration with isogeometric discretization.

[79]

Y. Otoguro, K. Takizawa, T.E. Tezduyar, K. Nagaoka, and S. Mei, “Turbocharger turbine and exhaust manifold flow computation with the Space–Time Variational Multiscale Method and Isogeometric Analysis”, Computers & Fluids, 179 (2019) 764–776, 10.1016/j.compfluid.2018.05.019
Times Cited in Web of Science Core Collection: 51, Times Cited in Scopus: 59
@ARTICLE{Otoguro18a, AUTHOR = {Y.~Otoguro and K.~Takizawa and T. E.~Tezduyar and K.~Nagaoka and S.~Mei}, JOURNAL = {Computers \& Fluids}, TITLE = {Turbocharger turbine and exhaust manifold flow computation with the {S}pace–{T}ime {V}ariational {M}ultiscale {M}ethod and {I}sogeometric {A}nalysis}, VOLUME = {179}, YEAR = {2019}, PAGES = {764–776}, DOI = {10.1016/j.compfluid.2018.05.019} } Abstract:
We address the computational challenges encountered in turbocharger turbine and exhaust manifold flow analysis. The core computational method is the Space–Time Variational Multiscale (ST-VMS) method, and the other key methods are the ST Isogeometric Analysis (ST-IGA), ST Slip Interface (ST-SI) method, ST/NURBS Mesh Update Method (STNMUM), and a general-purpose NURBS mesh generation method for complex geometries. The ST framework, in a general context, provides higher-order accuracy. The VMS feature of the ST-VMS addresses the computational challenges associated with the multiscale nature of the unsteady flow in the manifold and turbine, and the moving-mesh feature of the ST framework enables high-resolution computation near the rotor surface. The ST-SI enables moving-mesh computation of the spinning rotor. The mesh covering the rotor spins with it, and the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. The ST-IGA enables more accurate representation of the turbine and manifold geometries and increased accuracy in the flow solution. The STNMUM enables exact representation of the mesh rotation. The general-purpose NURBS mesh generation method makes it easier to deal with the complex geometries we have here. An SI also provides mesh generation flexibility in a general context by accurately connecting the two sides of the solution computed over nonmatching meshes. That is enabling us to use nonmatching NURBS meshes here. Stabilization parameters and element length definitions play a significant role in the ST-VMS and ST-SI. For the ST-VMS, we use the stabilization parameters introduced recently, and for the ST-SI, the element length definition we are introducing here. The model we actually compute with includes the exhaust gas purifier, which makes the turbine outflow conditions more realistic. We compute the flow for a full intake/exhaust cycle, which is much longer than the turbine rotation cycle because of high rotation speeds, and the long duration required is an additional computational challenge. The computation demonstrates that the methods we use here are very effective in this class of challenging flow analyses.

[78]

K. Takizawa, T.E. Tezduyar, H. Uchikawa, T. Terahara, T. Sasaki, and A. Yoshida, “Mesh refinement influence and cardiac-cycle flow periodicity in aorta flow analysis with isogeometric discretization”, Computers & Fluids, 179 (2019) 790–798, 10.1016/j.compfluid.2018.05.025
Times Cited in Web of Science Core Collection: 56, Times Cited in Scopus: 64
@ARTICLE{Takizawa18b, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and H.~Uchikawa and T.~Terahara and T.~Sasaki and A.~Yoshida}, JOURNAL = {Computers \& Fluids}, TITLE = {Mesh refinement influence and cardiac-cycle flow periodicity in aorta flow analysis with isogeometric discretization}, VOLUME = {179}, YEAR = {2019}, PAGES = {790–798}, DOI = {10.1016/j.compfluid.2018.05.025} } Abstract:
We present detailed studies on mesh refinement influence and cardiac-cycle flow periodicity in aorta flow analysis with isogeometric discretization. Both factors play a key role in the reliability and practical value of aorta flow analysis. The core computational method is the space–time Variational Multiscale (ST-VMS) method. The other key method is the ST Isogeometric Analysis (ST-IGA). The ST framework, in a general context, provides higher-order accuracy. The VMS feature of the ST-VMS addresses the computational challenges associated with the multiscale nature of the unsteady flow in the aorta. The ST-IGA provides smoother representation of the aorta and increased accuracy in the flow solution. We conduct the studies for a patient-specific aorta geometry. We determine the level of mesh refinement needed and assess the nature of the flow periodicity reached.

[77]

K. Takizawa, T.E. Tezduyar, and Y. Otoguro, “Stabilization and discontinuity-capturing parameters for space–time flow computations with finite element and isogeometric discretizations”, Computational Mechanics, 62 (2018) 1169–1186, 10.1007/s00466-018-1557-x
Times Cited in Web of Science Core Collection: 69, Times Cited in Scopus: 80
@ARTICLE{Takizawa17e, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and Y.~Otoguro}, JOURNAL = {Computational Mechanics}, TITLE = {Stabilization and discontinuity-capturing parameters for space–time flow computations with finite element and isogeometric discretizations}, VOLUME = {62}, YEAR = {2018}, PAGES = {1169–1186}, DOI = {10.1007/s00466-018-1557-x} } Abstract:
Stabilized methods, which have been very common in flow computations for many years, typically involve stabilization parameters, and discontinuity-capturing (DC) parameters if the method is supplemented with a DC term. Various well-performing stabilization and DC parameters have been introduced for stabilized space–time (ST) computational methods in the context of the advection–diffusion equation and the Navier–Stokes equations of incompressible and compressible flows. These parameters were all originally intended for finite element discretization but quite often used also for isogeometric discretization. The stabilization and DC parameters we present here for ST computations are in the context of the advection–diffusion equation and the Navier–Stokes equations of incompressible flows, target isogeometric discretization, and are also applicable to finite element discretization. The parameters are based on a direction-dependent element length expression. The expression is outcome of an easy to understand derivation. The key components of the derivation are mapping the direction vector from the physical ST element to the parent ST element, accounting for the discretization spacing along each of the parametric coordinates, and mapping what we have in the parent element back to the physical element. The test computations we present for pure-advection cases show that the parameters proposed result in good solution profiles.

[76]

Y. Otoguro, K. Takizawa, and T.E. Tezduyar, “Space–time VMS computational flow analysis with isogeometric discretization and a general-purpose NURBS mesh generation method”, Computers & Fluids, 158 (2017) 189–200, 10.1016/j.compfluid.2017.04.017
Times Cited in Web of Science Core Collection: 54, Times Cited in Scopus: 68
@ARTICLE{Otoguro16a, AUTHOR = {Y.~Otoguro and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computers \& Fluids}, TITLE = {Space–time {VMS} computational flow analysis with isogeometric discretization and a general-purpose {NURBS} mesh generation method}, VOLUME = {158}, YEAR = {2017}, PAGES = {189–200}, DOI = {10.1016/j.compfluid.2017.04.017} } Abstract:
The Space–Time Computational Analysis (STCA) with key components that include the ST Variational Multiscale (ST-VMS) method and ST Isogeometric Analysis (ST-IGA) is being increasingly used in fluid mechanics computations with complex geometries. In such computations, the ST-VMS serves as the core method, complemented by the ST-IGA, and sometimes by additional key components, such as the ST Slip Interface (ST-SI) method. To make the ST-IGA use, and in a wider context the IGA use, even more practical in fluid mechanics computations, NURBS volume mesh generation needs to be easier and as automated as possible. To that end, we present a general-purpose NURBS mesh generation method. The method is based on multi-block structured mesh generation with existing techniques, projection of that mesh to a NURBS mesh made of patches that correspond to the blocks, and recovery of the original model surfaces to the extent they are suitable for accurate and robust fluid mechanics computations. It is expected to retain the refinement distribution and element quality of the multi-block structured mesh that we start with. The flexibility of discretization with the general-purpose mesh generation is supplemented with the ST-SI method, which allows, without loss of accuracy, C−1 continuity between NURBS patches and thus removes the matching requirement between the patches. We present a test computation for a turbocharger turbine and exhaust manifold, which demonstrates that the general-purpose mesh generation method proposed makes the IGA use in fluid mechanics computations even more practical.

[75]

K. Takizawa, T.E. Tezduyar, and T. Kanai, “Porosity models and computational methods for compressible-flow aerodynamics of parachutes with geometric porosity”, Mathematical Models and Methods in Applied Sciences, 27 (2017) 771–806, 10.1142/S0218202517500166
Times Cited in Web of Science Core Collection: 65, Times Cited in Scopus: 78
@ARTICLE{Takizawa17a, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Kanai}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Porosity models and computational methods for compressible-flow aerodynamics of parachutes with geometric porosity}, VOLUME = {27}, NUMBER = {None}, YEAR = {2017}, PAGES = {771–806}, DOI = {10.1142/S0218202517500166} } Abstract:
Spacecraft-parachute designs quite often include “geometric porosity” created by the hundreds of gaps and slits that the flow goes through. Computational fluid-structure interaction (FSI) analysis of these parachutes with resolved geometric porosity would be exceedingly challenging, and therefore accurate modeling of the geometric porosity is essential for reliable FSI analysis. The space-time FSI (STFSI) method with the homogenized modeling of geometric porosity has proven to be reliable in computational analysis and design studies of Orion spacecraft parachutes in the incompressible-flow regime. Here we introduce porosity models and ST computational methods for compressible-flow aerodynamics of parachutes with geometric porosity. The main components of the ST computational framework we use are the compressible-flow ST SUPG method, which was introduced earlier, and the compressible-flow ST Slip Interface method, which we introduce here. The computations we present for a drogue parachute show the effectiveness of the porosity models and ST computational methods.

[74]

K. Takizawa, T.E. Tezduyar, T. Terahara, and T. Sasaki, “Heart valve flow computation with the integrated Space–Time VMS, Slip Interface, Topology Change and Isogeometric Discretization methods”, Computers & Fluids, 158 (2017) 176–188, 10.1016/j.compfluid.2016.11.012
Times Cited in Web of Science Core Collection: 72, Times Cited in Scopus: 88
@ARTICLE{Takizawa16g2, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Terahara and T.~Sasaki}, JOURNAL = {Computers \& Fluids}, TITLE = {Heart valve flow computation with the integrated {S}pace–{T}ime {VMS}, {S}lip {I}nterface, {T}opology {C}hange and {I}sogeometric {D}iscretization methods}, VOLUME = {158}, YEAR = {2017}, PAGES = {176–188}, DOI = {10.1016/j.compfluid.2016.11.012} } Abstract:
Heart valve flow computation requires accurate representation of boundary layers near moving solid surfaces, including the valve leaflet surfaces, even when the leaflets come into contact. It also requires dealing with a high level of geometric complexity. We address these computational challenges with a Space–Time (ST) method developed by integrating three special ST methods in the framework of the ST Variational Multiscale (ST-VMS) method. The special methods are the ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods and ST Isogeometric Analysis (ST-IGA). The computations are for a realistic aortic-valve model with prescribed valve leaflet motion and actual contact between the leaflets. The ST-VMS method functions as a moving-mesh method, which maintains high-resolution boundary layer representation near the solid surfaces, including leaflet surfaces. The ST-TC method was introduced for moving-mesh computation of flow problems with TC, such as contact between the leaflets of a heart valve. It deals with the contact while maintaining high-resolution representation near the leaflet surfaces. The ST-SI method was originally introduced to have high-resolution representation of the boundary layers near spinning solid surfaces. The mesh covering a spinning solid surface spins with it, and the SI between the spinning mesh and the rest of the mesh accurately connects the two sides. In the context of heart valves, the SI connects the sectors of meshes containing the leaflets, enabling a more effective mesh moving. In that context, integration of the ST-SI and ST-TC methods enables high-resolution representation even when the contact is between leaflets that are covered by meshes with SI. It also enables dealing with contact location change or contact and sliding on the SI. By integrating the ST-IGA with the ST-SI and ST-TC methods, in addition to having a more accurate representation of the surfaces and increased accuracy in the flow solution, the element density in the narrow spaces near the contact areas is kept at a reasonable level. Furthermore, because the flow representation in the contact area has a wider support in IGA, the flow computation method becomes more robust. The computations we present for an aortic-valve model with two different modes of prescribed leaflet motion show the effectiveness of the ST-SI-TC-IGA method.

[73]

K. Takizawa, T.E. Tezduyar, and T. Sasaki, “Aorta modeling with the element-based zero-stress state and isogeometric discretization”, Computational Mechanics, 59 (2017) 265–280, 10.1007/s00466-016-1344-5
Times Cited in Web of Science Core Collection: 34, Times Cited in Scopus: 38
@ARTICLE{Takizawa16f2, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Sasaki}, JOURNAL = {Computational Mechanics}, TITLE = {Aorta modeling with the element-based zero-stress state and isogeometric discretization}, VOLUME = {59}, YEAR = {2017}, PAGES = {265–280}, DOI = {10.1007/s00466-016-1344-5} } Abstract:
Patient-specific arterial fluid–structure interaction computations, including aorta computations, require an estimation of the zero-stress state (ZSS), because the image-based arterial geometries do not come from a ZSS. We have earlier introduced a method for estimation of the element-based ZSS (EBZSS) in the context of finite element discretization of the arterial wall. The method has three main components. 1. An iterative method, which starts with a calculated initial guess, is used for computing the EBZSS such that when a given pressure load is applied, the image-based target shape is matched. 2. A method for straight-tube segments is used for computing the EBZSS so that we match the given diameter and longitudinal stretch in the target configuration and the “opening angle.” 3. An element-based mapping between the artery and straight-tube is extracted from the mapping between the artery and straight-tube segments. This provides the mapping from the arterial configuration to the straight-tube configuration, and from the estimated EBZSS of the straight-tube configuration back to the arterial configuration, to be used as the initial guess for the iterative method that matches the image-based target shape. Here we present the version of the EBZSS estimation method with isogeometric wall discretization. With isogeometric discretization, we can obtain the element-based mapping directly, instead of extracting it from the mapping between the artery and straight-tube segments. That is because all we need for the element-based mapping, including the curvatures, can be obtained within an element. With NURBS basis functions, we may be able to achieve a similar level of accuracy as with the linear basis functions, but using larger-size and much fewer elements. Higher-order NURBS basis functions allow representation of more complex shapes within an element. To show how the new EBZSS estimation method performs, we first present 2D test computations with straight-tube configurations. Then we show how the method can be used in a 3D computation where the target geometry is coming from medical image of a human aorta.

[72]

A. Castorrini, A. Corsini, F. Rispoli, P. Venturini, K. Takizawa, and T.E. Tezduyar, “Computational analysis of wind-turbine blade rain erosion”, Computers & Fluids, 141 (2016) 175–183, 10.1016/j.compfluid.2016.08.013
Times Cited in Web of Science Core Collection: 64, Times Cited in Scopus: 71
@ARTICLE{Castorrini16b, AUTHOR = {A.~Castorrini and A.~Corsini and F.~Rispoli and P.~Venturini and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computers \& Fluids}, TITLE = {Computational analysis of wind-turbine blade rain erosion}, VOLUME = {141}, YEAR = {2016}, PAGES = {175–183}, DOI = {10.1016/j.compfluid.2016.08.013} } Abstract:
Wind-turbine blade rain erosion damage could be significant if the blades are not protected. This damage would not typically influence the structural integrity of the blades, but it could degrade the aerodynamic performance and therefore the power production. We present computational analysis of rain erosion in wind-turbine blades. The main components of the method used in the analysis are the Streamline-Upwind/Petrov–Galerkin (SUPG) and Pressure-Stabilizing/Petrov–Galerkin (PSPG) stabilizations, a finite element particle-cloud tracking method, and an erosion model. The turbulent-flow nature of the analysis is handled with a RANS model and SUPG/PSPG stabilization, the particle-cloud trajectories are calculated based on the computed flow field and closure models defined for the turbulent dispersion of particles, and one-way dependence is assumed between the flow and particle dynamics. The erosion patterns are then computed based on the particle-cloud data. The patterns are consistent with those observed in the actual wind turbines.

[71]

K. Takizawa, T.E. Tezduyar, and T. Terahara, “Ram-air parachute structural and fluid mechanics computations with the space–time isogeometric analysis (ST-IGA)”, Computers & Fluids, 141 (2016) 191–200, 10.1016/j.compfluid.2016.05.027
Times Cited in Web of Science Core Collection: 69, Times Cited in Scopus: 85
@ARTICLE{Takizawa16e, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Terahara}, JOURNAL = {Computers \& Fluids}, TITLE = {Ram-Air Parachute Structural and Fluid Mechanics Computations with the Space–Time Isogeometric Analysis ({ST-IGA})}, VOLUME = {141}, YEAR = {2016}, PAGES = {191–200}, DOI = {10.1016/j.compfluid.2016.05.027} } Abstract:
We present a method for structural and fluid mechanics computations of ram-air parachutes. A ram-air parachute is a parafoil inflated by the airflow through the inlets at the leading edge. It has better control and gliding capability than round parachutes. Reliable analysis of ram-air parachutes requires accurate representation of the parafoil geometry, fabric porosity and the complex, multiscale flow behavior involved in this class of problems. The key components of the method are (i) the Space–Time Variational Multiscale (ST-VMS) method, (ii) the version of the ST Slip Interface (ST-SI) method where the SI is between a thin porous structure and the fluid on its two sides, (iii) the ST Isogeometric Analysis (ST-IGA), and (iv) special-purpose NURBS mesh generation techniques for the parachute structure and the flow field inside and outside the parafoil. The ST-VMS method is a stabilized formulation that also serves as a turbulence model and can deal effectively with the complex, multiscale flow behavior. With the ST-SI version for porosity modeling, we deal with the fabric porosity in a fashion consistent with how we deal with the standard SIs and how we enforce the Dirichlet boundary conditions weakly. The ST-IGA, with NURBS basis functions in space, gives us, with relatively few number of unknowns, accurate representation of the parafoil geometry and increased accuracy in the flow solution. The special-purpose mesh generation techniques enable NURBS representation of the structure and fluid domains with significant geometric complexity. The test computations we present are for building a starting parachute shape and a starting flow field associated with that parachute shape, which are the first two key steps in fluid–structure interaction analysis. The computations demonstrate the effectiveness of the method in this class of problems.

[70]

K. Takizawa, T.E. Tezduyar, S. Asada, and T. Kuraishi, “Space–time method for flow computations with slip interfaces and topology changes (ST-SI-TC)”, Computers & Fluids, 141 (2016) 124–134, 10.1016/j.compfluid.2016.05.006
Times Cited in Web of Science Core Collection: 55, Times Cited in Scopus: 65
@ARTICLE{Takizawa16d, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and S.~Asada and T.~Kuraishi}, JOURNAL = {Computers \& Fluids}, TITLE = {Space–Time Method for Flow Computations with Slip Interfaces and Topology Changes ({ST-SI-TC})}, VOLUME = {141}, YEAR = {2016}, PAGES = {124–134}, DOI = {10.1016/j.compfluid.2016.05.006} } Abstract:
The Space–Time Variational Multiscale (ST-VMS) method was introduced to function as a moving-mesh method. It is the VMS version of the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) method. It has reasonably good turbulence modeling features and serves as a core computational method. The ST Slip Interface (ST-SI) method was introduced to addresses the challenge involved in high-resolution representation of the boundary layers near spinning solid surfaces. The mesh covering a spinning solid surface spins with it and thus maintains the high-resolution representation near it. The ST-TC method was introduced for moving-mesh computation of flow problems with topology changes, such as contact between solid surfaces. It deals with the TC while maintaining high-resolution boundary layer representation near solid surfaces. The “ST-SI-TC” method we introduce here integrates the ST-SI and ST-TC methods in the ST-VMS framework. It enables accurate flow analysis when we have a spinning solid surface that is in contact with a solid surface. We present two test computations with the ST-SI-TC method, and they are both with models of flow around a rotating tire with road contact and prescribed deformation, one with a 2D model, and one with a 3D model.

[69]

K. Takizawa, T.E. Tezduyar, Y. Otoguro, T. Terahara, T. Kuraishi, and H. Hattori, “Turbocharger flow computations with the Space–Time Isogeometric Analysis (ST-IGA)”, Computers & Fluids, 142 (2017) 15–20, 10.1016/j.compfluid.2016.02.021
Times Cited in Web of Science Core Collection: 85, Times Cited in Scopus: 101
@ARTICLE{Takizawa16c, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and Y.~Otoguro and T.~Terahara and T.~Kuraishi and H.~Hattori}, JOURNAL = {Computers \& Fluids}, TITLE = {Turbocharger Flow Computations with the {S}pace–{T}ime {I}sogeometric {A}nalysis ({ST-IGA})}, VOLUME = {142}, YEAR = {2017}, PAGES = {15–20}, DOI = {10.1016/j.compfluid.2016.02.021} } Abstract:
We focus on turbocharger computational flow analysis with a method that possesses higher accuracy in spatial and temporal representations. In the method we have developed for this purpose, we use a combination of (i) the Space–Time Variational Multiscale (ST-VMS) method, which is a stabilized formulation that also serves as a turbulence model, (ii) the ST Slip Interface (ST-SI) method, which maintains high-resolution representation of the boundary layers near spinning solid surfaces by allowing in a consistent fashion slip at the interface between the mesh covering a spinning surface and the mesh covering the rest of the domain, and (iii) the Isogeometric Analysis (IGA), where we use NURBS basis functions in space and time. The basis functions are spatially higher-order in all representations, and temporally higher-order in representation of the solid-surface and mesh motions. The ST nature of the method gives us higher-order accuracy in the flow solver, and when combined with temporally higher-order basis functions, a more accurate representation of the surface motion, and a mesh motion consistent with that. The spatially higher-order basis functions give us again higher-order accuracy in the flow solver, a more accurate, in some parts exact, representation of the surface geometry, and better representation in evaluating the second-order spatial derivatives. Using NURBS basis functions with a complex geometry is not trivial, however, once we generate the mesh, the computational efficiency is substantially increased. We focus on the turbine part of a turbocharger, but our method can also be applied to the compressor part and thus can be extended to the full turbocharger.

[68]

K. Takizawa, T.E. Tezduyar, and H. Hattori, “Computational analysis of flow-driven string dynamics in turbomachinery”, Computers & Fluids, 142 (2017) 109–117, 10.1016/j.compfluid.2016.02.019
Times Cited in Web of Science Core Collection: 49, Times Cited in Scopus: 58
@ARTICLE{Takizawa16b, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and H.~Hattori}, JOURNAL = {Computers \& Fluids}, TITLE = {Computational Analysis of Flow-Driven String Dynamics in Turbomachinery}, VOLUME = {142}, YEAR = {2017}, PAGES = {109–117}, DOI = {10.1016/j.compfluid.2016.02.019} } Abstract:
We focus on computational analysis of flow-driven string dynamics. The objective is to understand how the strings carried by a fluid interact with the solid surfaces present and get stuck on or around those surfaces. Our target application is turbomachinery, such as understanding how strings get stuck on or around the blades of a fan. The components of the method we developed for this purpose are the Space–Time Variational Multiscale (ST-VMS) and ST Slip Interface (ST-SI) methods for the fluid dynamics, and a one-way-dependence model and the Isogeometric Analysis (IGA) for the string dynamics. The ST-VMS method is the core computational technology and it also has the features of a turbulence model. The ST-SI method allows in a consistent fashion slip at the interface between the mesh covering a spinning solid surface and the mesh covering the rest of the domain, and with this, we maintain high-resolution representation of the boundary layers near spinning solid surfaces such as fan blades. With the one-way-dependence model, we compute the influence of the flow on the string dynamics, while avoiding the formidable task of computing the influence of the string on the flow, which we expect to be small. The IGA for the string dynamics gives us not only a higher-order method and smoothness in the structure shape, but also smoothness in the fluid dynamics forces calculated on the string. To demonstrate how the method can be used in computational analysis of flow-driven string dynamics, we present the pilot computations we carried out, for a duct with cylindrical obstacles and for a ventilating fan.

[67]

K. Takizawa, T.E. Tezduyar, T. Kuraishi, S. Tabata, and H. Takagi, “Computational thermo-fluid analysis of a disk brake”, Computational Mechanics, 57 (2016) 965–977, 10.1007/s00466-016-1272-4
Times Cited in Web of Science Core Collection: 66, Times Cited in Scopus: 81
@ARTICLE{Takizawa16a, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Kuraishi and S.~Tabata and H.~Takagi}, JOURNAL = {Computational Mechanics}, TITLE = {Computational thermo-fluid analysis of a disk brake}, VOLUME = {57}, YEAR = {2016}, PAGES = {965–977}, DOI = {10.1007/s00466-016-1272-4} } Abstract:
We present computational thermo-fluid analysis of a disk brake, including thermo-fluid analysis of the flow around the brake and heat conduction analysis of the disk. The computational challenges include proper representation of the small-scale thermo-fluid behavior, high-resolution representation of the thermo-fluid boundary layers near the spinning solid surfaces, and bringing the heat transfer coefficient (HTC) calculated in the thermo-fluid analysis of the flow to the heat conduction analysis of the spinning disk. The disk brake model used in the analysis closely represents the actual configuration, and this adds to the computational challenges. The components of the method we have developed for computational analysis of the class of problems with these types of challenges include the Space–Time Variational Multiscale method for coupled incompressible flow and thermal transport, ST Slip Interface method for high-resolution representation of the thermo-fluid boundary layers near spinning solid surfaces, and a set of projection methods for different parts of the disk to bring the HTC calculated in the thermo-fluid analysis. With the HTC coming from the thermo-fluid analysis of the flow around the brake, we do the heat conduction analysis of the disk, from the start of the breaking until the disk spinning stops, demonstrating how the method developed works in computational analysis of this complex and challenging problem.

[66]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “New directions and challenging computations in fluid dynamics modeling with stabilized and multiscale methods”, Mathematical Models and Methods in Applied Sciences, 25 (2015) 2217–2226, 10.1142/S0218202515020029
Times Cited in Web of Science Core Collection: 60, Times Cited in Scopus: 68
@ARTICLE{Bazilevs15b, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {New Directions and Challenging Computations in Fluid Dynamics Modeling with Stabilized and Multiscale Methods}, VOLUME = {25}, NUMBER = {None}, YEAR = {2015}, PAGES = {2217–2226}, DOI = {10.1142/S0218202515020029} } Abstract:
In this paper, we provide a brief overview of the development of stabilized and multiscale methods in fluid dynamics. We mainly focus on recent developments and new directions in the variational multiscale (VMS) methods. We also discuss applications of the VMS techniques to fluid dynamics problems involving computational challenges associated with high-Reynolds-number flows, wall-bounded turbulent flows, flows with moving domains including subdomains in relative motion, and free-surface flows.

[65]

K. Takizawa, T.E. Tezduyar, H. Mochizuki, H. Hattori, S. Mei, L. Pan, and K. Montel, “Space–time VMS method for flow computations with slip interfaces (ST-SI)”, Mathematical Models and Methods in Applied Sciences, 25 (2015) 2377–2406, 10.1142/S0218202515400126
Times Cited in Web of Science Core Collection: 89, Times Cited in Scopus: 106
@ARTICLE{Takizawa15b, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and H.~Mochizuki and H.~Hattori and S.~Mei and L.~Pan and K.~Montel}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Space–time {VMS} method for flow computations with slip interfaces ({ST-SI})}, VOLUME = {25}, NUMBER = {None}, YEAR = {2015}, PAGES = {2377–2406}, DOI = {10.1142/S0218202515400126} } Abstract:
We present the space-time variational multiscale (ST-VMS) method for flow computations with slip interfaces (ST-SI). The method is intended for fluid-structure interaction (FSI) analysis where one or more of the subdomains contain spinning structures, such as the rotor of a wind turbine, and the subdomains are covered by meshes that do not match at the interface and have slip between them. The mesh covering a subdomain with the spinning structure spins with it, thus maintaining the high-resolution representation of the boundary layers near the structure. The starting point in the development of the method is the version of the arbitrary Lagrangian-Eulerian VMS (ALE-VMS) method designed for computations with “sliding interfaces”. Interface terms similar to those in the ALE-VMS version are added to the ST-VMS formulation to account for the compatibility conditions for the velocity and stress. In addition to having a high-resolution representation of the boundary layers, because the ST framework allows NURBS functions in temporal representation of the structure motion, we have exact representation of the circular paths associated with the spinning. The ST-SI method includes versions for cases where the SI is between fluid and solid domains with weakly-imposed Dirichlet conditions for the fluid and for cases where the SI is between a thin porous structure and the fluid on its two sides. Test computations with 2D and 3D models of a vertical-axis wind turbine show the effectiveness of the ST-SI method.

[64]

K. Takizawa, T.E. Tezduyar, and T. Kuraishi, “Multiscale ST methods for thermo-fluid analysis of a ground vehicle and its tires”, Mathematical Models and Methods in Applied Sciences, 25 (2015) 2227–2255, 10.1142/S0218202515400072
Times Cited in Web of Science Core Collection: 97, Times Cited in Scopus: 117
@ARTICLE{Takizawa15a, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Kuraishi}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Multiscale {ST} Methods for Thermo-Fluid Analysis of a Ground Vehicle and its Tires}, VOLUME = {25}, NUMBER = {None}, YEAR = {2015}, PAGES = {2227–2255}, DOI = {10.1142/S0218202515400072} } Abstract:
We present the core and special multiscale space-time (ST) methods we developed for thermo-fluid analysis of a ground vehicle and its tires. We also present application of these methods to thermo-fluid analysis of a freight truck and its rear set of tires. The core multiscale ST method is the ST variational multiscale (ST-VMS) formulation of the Navier-Stokes equations of incompressible flows with thermal coupling, which is multiscale in the way the small-scale thermo-fluid behavior is represented in the computations. The special multiscale ST method is spatially multiscale, where the thermo-fluid computation over the global domain with a reasonable mesh refinement is followed by a higher-resolution computation over the local domain containing the rear set of tires, with the boundary and initial conditions coming from the data computed over the global domain. The large amount of time-history data from the global computation is stored using the ST computation technique with continuous representation in time (ST-C), which serves as a data compression technique in this context. In our thermo-fluid analysis, we use a road-surface temperature higher than the free-stream temperature, and a tire-surface temperature that is even higher. We also include in the analysis the heat from the engine and exhaust system, with a reasonably realistic representation of the rate by which that heat transfer takes place as well as the surface geometry of the engine and exhaust system over which the heat transfer occurs. We take into account the heave motion of the truck body. We demonstrate how the spatially multiscale ST method, with higher-refinement mesh in the local domain, substantially increases the accuracy of the computed heat transfer rates from the tires.

[63]

K. Takizawa, T.E. Tezduyar, and R. Kolesar, “FSI modeling of the Orion spacecraft drogue parachutes”, Computational Mechanics, 55 (2015) 1167–1179, 10.1007/s00466-014-1108-z
Times Cited in Web of Science Core Collection: 59, Times Cited in Scopus: 72
@ARTICLE{Takizawa14h, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and R.~Kolesar}, JOURNAL = {Computational Mechanics}, TITLE = {{FSI} Modeling of the {Orion} Spacecraft Drogue Parachutes}, VOLUME = {55}, YEAR = {2015}, PAGES = {1167–1179}, DOI = {10.1007/s00466-014-1108-z} } Abstract:
The space–time fluid–structure interaction (STFSI) methods for parachute modeling are now capable of bringing reliable analysis to spacecraft parachutes, which pose formidable computational challenges. A number of special FSI methods targeting spacecraft parachutes complement the STFSI core computational technology in addressing these challenges. Until recently, these challenges were addressed for the Orion spacecraft main parachutes, which are the parachutes used for landing, and in the incompressible-flow regime, which is where the main parachutes operate. At higher altitudes the Orion spacecraft will rely on drogue parachutes. These parachutes have a ribbon construction, and in FSI modeling this creates geometric and flow complexities comparable to those encountered in FSI modeling of the main parachutes, which have a ringsail construction. Like the main parachutes, the drogue parachutes will be used in multiple stages—two reefed stages and a fully-open stage. A reefed stage is where a cable along the parachute skirt constrains the diameter to be less than the diameter in the subsequent stage. After a period of time during the descent at the reefed stage, the cable is cut and the parachute disreefs (i.e. expands) to the next stage. The reefed stages and disreefing involve computational challenges beyond those in FSI modeling of fully-open drogue parachutes. We present the special modeling techniques we devised to address the computational challenges and the results from the computations carried out. The flight envelope of the Orion drogue parachutes includes regions where the Mach number is high enough to require a compressible-flow solver. We present a preliminary fluid mechanics computation for such a case.

[62]

K. Takizawa, T.E. Tezduyar, and A. Buscher, “Space–time computational analysis of MAV flapping-wing aerodynamics with wing clapping”, Computational Mechanics, 55 (2015) 1131–1141, 10.1007/s00466-014-1095-0
Times Cited in Web of Science Core Collection: 85, Times Cited in Scopus: 97
@ARTICLE{Takizawa14j, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and A.~Buscher}, JOURNAL = {Computational Mechanics}, TITLE = {Space–Time Computational Analysis of {MAV} Flapping-Wing Aerodynamics with Wing Clapping}, VOLUME = {55}, YEAR = {2015}, PAGES = {1131–1141}, DOI = {10.1007/s00466-014-1095-0} } Abstract:
Computational analysis of flapping-wing aerodynamics with wing clapping was one of the classes of computations targeted in introducing the space–time (ST) interface-tracking method with topology change (ST-TC). The ST-TC method is a new version of the deforming-spatial-domain/stabilized ST (DSD/SST) method, enhanced with a master–slave system that maintains the connectivity of the “parent” fluid mechanics mesh when there is contact between the moving interfaces. With that enhancement and because of its ST nature, the ST-TC method can deal with an actual contact between solid surfaces in flow problems with moving interfaces. It accomplishes that while still possessing the desirable features of interface-tracking (moving-mesh) methods, such as better resolution of the boundary layers. Earlier versions of the DSD/SST method, with effective mesh update, were already able to handle moving-interface problems when the solid surfaces are in near contact or create near TC. Flapping-wing aerodynamics of an actual locust, with the forewings and hindwings crossing each other very close and creating near TC, is an example of successfully computed problems. Flapping-wing aerodynamics of a micro aerial vehicle (MAV) with the wings of an actual locust is another example. Here we show how the ST-TC method enables 3D computational analysis of flapping-wing aerodynamics of an MAV with wing clapping. In the analysis, the wings are brought into an actual contact when they clap. We present results for a model dragonfly MAV.

[61]

K. Takizawa, T.E. Tezduyar, C. Boswell, Y. Tsutsui, and K. Montel, “Special methods for aerodynamic-moment calculations from parachute FSI modeling”, Computational Mechanics, 55 (2015) 1059–1069, 10.1007/s00466-014-1074-5
Times Cited in Web of Science Core Collection: 61, Times Cited in Scopus: 69
@ARTICLE{Takizawa14g, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and C.~Boswell and Y.~Tsutsui and K.~Montel}, JOURNAL = {Computational Mechanics}, TITLE = {Special Methods for Aerodynamic-Moment Calculations from Parachute {FSI} Modeling}, VOLUME = {55}, YEAR = {2015}, PAGES = {1059–1069}, DOI = {10.1007/s00466-014-1074-5} } Abstract:
The space–time fluid–structure interaction (STFSI) methods for 3D parachute modeling are now at a level where they can bring reliable, practical analysis to some of the most complex parachute systems, such as spacecraft parachutes. The methods include the Deforming-Spatial-Domain/Stabilized ST method as the core computational technology, and a good number of special FSI methods targeting parachutes. Evaluating the stability characteristics of a parachute based on how the aerodynamic moment varies as a function of the angle of attack is one of the practical analyses that reliable parachute FSI modeling can deliver. We describe the special FSI methods we developed for this specific purpose and present the aerodynamic-moment data obtained from FSI modeling of NASA Orion spacecraft parachutes and Japan Aerospace Exploration Agency (JAXA) subscale parachutes.

[60]

K. Takizawa, T.E. Tezduyar, R. Kolesar, C. Boswell, T. Kanai, and K. Montel, “Multiscale methods for gore curvature calculations from FSI modeling of spacecraft parachutes”, Computational Mechanics, 54 (2014) 1461–1476, 10.1007/s00466-014-1069-2
Times Cited in Web of Science Core Collection: 54, Times Cited in Scopus: 62
@ARTICLE{Takizawa14e, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and R.~Kolesar and C.~Boswell and T.~Kanai and K.~Montel}, JOURNAL = {Computational Mechanics}, TITLE = {Multiscale Methods for Gore Curvature Calculations from {FSI} Modeling of Spacecraft Parachutes}, VOLUME = {54}, YEAR = {2014}, PAGES = {1461–1476}, DOI = {10.1007/s00466-014-1069-2} } Abstract:
There are now some sophisticated and powerful methods for computer modeling of parachutes. These methods are capable of addressing some of the most formidable computational challenges encountered in parachute modeling, including fluid–structure interaction (FSI) between the parachute and air flow, design complexities such as those seen in spacecraft parachutes, and operational complexities such as use in clusters and disreefing. One should be able to extract from a reliable full-scale parachute modeling any data or analysis needed. In some cases, however, the parachute engineers may want to perform quickly an extended or repetitive analysis with methods based on simplified models. Some of the data needed by a simplified model can very effectively be extracted from a full-scale computer modeling that serves as a pilot. A good example of such data is the circumferential curvature of a parachute gore, where a gore is the slice of the parachute canopy between two radial reinforcement cables running from the parachute vent to the skirt. We present the multiscale methods we devised for gore curvature calculation from FSI modeling of spacecraft parachutes. The methods include those based on the multiscale sequentially-coupled FSI technique and using NURBS meshes. We show how the methods work for the fully-open and two reefed stages of the Orion spacecraft main and drogue parachutes.

[59]

A. Corsini, F. Rispoli, A.G. Sheard, K. Takizawa, T.E. Tezduyar, and P. Venturini, “A variational multiscale method for particle-cloud tracking in turbomachinery flows”, Computational Mechanics, 54 (2014) 1191–1202, 10.1007/s00466-014-1050-0
Times Cited in Web of Science Core Collection: 41, Times Cited in Scopus: 46
@ARTICLE{Corsini14a, AUTHOR = {A.~Corsini and F.~Rispoli and A. G.~Sheard and K.~Takizawa and T. E.~Tezduyar and P.~Venturini}, JOURNAL = {Computational Mechanics}, TITLE = {A variational multiscale method for particle-cloud tracking in turbomachinery flows}, VOLUME = {54}, YEAR = {2014}, PAGES = {1191–1202}, DOI = {10.1007/s00466-014-1050-0} } Abstract:
We present a computational method for simulation of particle-laden flows in turbomachinery. The method is based on a stabilized finite element fluid mechanics formulation and a finite element particle-cloud tracking method. We focus on induced-draft fans used in process industries to extract exhaust gases in the form of a two-phase fluid with a dispersed solid phase. The particle-laden flow causes material wear on the fan blades, degrading their aerodynamic performance, and therefore accurate simulation of the flow would be essential in reliable computational turbomachinery analysis and design. The turbulent-flow nature of the problem is dealt with a Reynolds-Averaged Navier–Stokes model and Streamline-Upwind/Petrov–Galerkin/Pressure-Stabilizing/Petrov–Galerkin stabilization, the particle-cloud trajectories are calculated based on the flow field and closure models for the turbulence–particle interaction, and one-way dependence is assumed between the flow field and particle dynamics. We propose a closure model utilizing the scale separation feature of the variational multiscale method, and compare that to the closure utilizing the eddy viscosity model. We present computations for axial- and centrifugal-fan configurations, and compare the computed data to those obtained from experiments, analytical approaches, and other computational methods.

[58]

K. Takizawa, R. Torii, H. Takagi, T.E. Tezduyar, and X.Y. Xu, “Coronary arterial dynamics computation with medical-image-based time-dependent anatomical models and element-based zero-stress state estimates”, Computational Mechanics, 54 (2014) 1047–1053, 10.1007/s00466-014-1049-6
Times Cited in Web of Science Core Collection: 36, Times Cited in Scopus: 41
@ARTICLE{Takizawa14m, AUTHOR = {K.~Takizawa and R.~Torii and H.~Takagi and T. E.~Tezduyar and X. Y.~Xu}, JOURNAL = {Computational Mechanics}, TITLE = {Coronary arterial dynamics computation with medical-image-based time-dependent anatomical models and element-based zero-stress state estimates}, VOLUME = {54}, YEAR = {2014}, PAGES = {1047–1053}, DOI = {10.1007/s00466-014-1049-6} } Abstract:
We propose a method for coronary arterial dynamics computation with medical-image-based time-dependent anatomical models. The objective is to improve the computational analysis of coronary arteries for better understanding of the links between the atherosclerosis development and mechanical stimuli such as endothelial wall shear stress and structural stress in the arterial wall. The method has two components. The first one is element-based zero-stress (ZS) state estimation, which is an alternative to prestress calculation. The second one is a “mixed ZS state” approach, where the ZS states for different elements in the structural mechanics mesh are estimated with reference configurations based on medical images coming from different instants within the cardiac cycle. We demonstrate the robustness of the method in a patient-specific coronary arterial dynamics computation where the motion of a thin strip along the arterial surface and two cut surfaces at the arterial ends is specified to match the motion extracted from the medical images.

[57]

K. Takizawa, T.E. Tezduyar, C. Boswell, R. Kolesar, and K. Montel, “FSI modeling of the reefed stages and disreefing of the Orion spacecraft parachutes”, Computational Mechanics, 54 (2014) 1203–1220, 10.1007/s00466-014-1052-y
Times Cited in Web of Science Core Collection: 65, Times Cited in Scopus: 76
@ARTICLE{Takizawa14f, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and C.~Boswell and R.~Kolesar and K.~Montel}, JOURNAL = {Computational Mechanics}, TITLE = {{FSI} Modeling of the Reefed Stages and Disreefing of the {Orion} Spacecraft Parachutes}, VOLUME = {54}, YEAR = {2014}, PAGES = {1203–1220}, DOI = {10.1007/s00466-014-1052-y} } Abstract:
Orion spacecraft main and drogue parachutes are used in multiple stages, starting with a “reefed” stage where a cable along the parachute skirt constrains the diameter to be less than the diameter in the subsequent stage. After a period of time during the descent, the cable is cut and the parachute “disreefs” (i.e. expands) to the next stage. Fluid–structure interaction (FSI) modeling of the reefed stages and disreefing involve computational challenges beyond those in FSI modeling of fully-open spacecraft parachutes. These additional challenges are created by the increased geometric complexities and by the rapid changes in the parachute geometry during disreefing. The computational challenges are further increased because of the added geometric porosity of the latest design of the Orion spacecraft main parachutes. The “windows” created by the removal of panels compound the geometric and flow complexity. That is because the Homogenized Modeling of Geometric Porosity, introduced to deal with the flow through the hundreds of gaps and slits involved in the construction of spacecraft parachutes, cannot accurately model the flow through the windows, which needs to be actually resolved during the FSI computation. In parachute FSI computations, the resolved geometric porosity is significantly more challenging than the modeled geometric porosity, especially in computing the reefed stages and disreefing. Orion spacecraft main and drogue parachutes will both have three stages, with computation of the Stage 1 shape and disreefing from Stage 1 to Stage 2 for the main parachute being the most challenging because of the lowest “reefing ratio” (the ratio of the reefed skirt diameter to the nominal diameter). We present the special modeling techniques and strategies we devised to address the computational challenges encountered in FSI modeling of the reefed stages and disreefing of the main and drogue parachutes. We report, for a single parachute, FSI computation of both reefed stages and both disreefing events for both the main and drogue parachutes. In the case of the main parachute, we also report, for a 2-parachute cluster, FSI computation of the disreefing from Stage 2 to Stage 3. With results from these computations, we demonstrate that we have to a great extent overcome one of the most formidable challenges in FSI modeling of spacecraft parachutes.

[56]

K. Takizawa, T.E. Tezduyar, A. Buscher, and S. Asada, “Space–time fluid mechanics computation of heart valve models”, Computational Mechanics, 54 (2014) 973–986, 10.1007/s00466-014-1046-9
Times Cited in Web of Science Core Collection: 95, Times Cited in Scopus: 106
@ARTICLE{Takizawa14i, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and A.~Buscher and S.~Asada}, JOURNAL = {Computational Mechanics}, TITLE = {Space–Time Fluid Mechanics Computation of Heart Valve Models}, VOLUME = {54}, YEAR = {2014}, PAGES = {973–986}, DOI = {10.1007/s00466-014-1046-9} } Abstract:
Fluid mechanics computation of heart valves with an interface-tracking (moving-mesh) method was one of the classes of computations targeted in introducing the space–time (ST) interface tracking method with topology change (ST-TC). The ST-TC method is a new version of the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) method. It can deal with an actual contact between solid surfaces in flow problems with moving interfaces, while still possessing the desirable features of interface-tracking methods, such as better resolution of the boundary layers. The DSD/SST method with effective mesh update can already handle moving-interface problems when the solid surfaces are in near contact or create near TC, if the “nearness” is sufficiently “near” for the purpose of solving the problem. That, however, is not the case in fluid mechanics of heart valves, as the solid surfaces need to be brought into an actual contact when the flow has to be completely blocked. Here we extend the ST-TC method to 3D fluid mechanics computation of heart valve models. We present computations for two models: an aortic valve with coronary arteries and a mechanical aortic valve. These computations demonstrate that the ST-TC method can bring interface-tracking accuracy to fluid mechanics of heart valves, and can do that with computational practicality.

[55]

H. Suito, K. Takizawa, V.Q.H. Huynh, D. Sze, and T. Ueda, “FSI analysis of the blood flow and geometrical characteristics in the thoracic aorta”, Computational Mechanics, 54 (2014) 1035–1045, 10.1007/s00466-014-1017-1
Times Cited in Web of Science Core Collection: 71, Times Cited in Scopus: 78
@ARTICLE{Suito14a, AUTHOR = {H.~Suito and K.~Takizawa and V. Q. H.~Huynh and D.~Sze and T.~Ueda}, JOURNAL = {Computational Mechanics}, TITLE = {{FSI} analysis of the blood flow and geometrical characteristics in the thoracic aorta}, VOLUME = {54}, YEAR = {2014}, PAGES = {1035–1045}, DOI = {10.1007/s00466-014-1017-1} } Abstract:
We present a fluid–structure interaction (FSI) analysis of the blood flow and geometrical characteristics in the thoracic aorta. The FSI is handled with the sequentially-coupled arterial FSI technique. The fluid mechanics equations are solved with the ST-VMS method, which is the variational multiscale version of the deforming-spatial-domain/stabilized space–time (DSD/SST) method. We focus on the relationship between the centerline geometry of the aorta and the flow field, which influences the wall shear stress distribution. The centerlines of the aorta models we use in our analysis are extracted from the CT scans, and we assume a constant diameter. Torsion-free model geometries are generated by projecting the original centerline to its averaged plane of curvature. The flow fields for the original and projected geometries are compared to examine the influence of the torsion.

[54]

K. Takizawa, “Computational engineering analysis with the new-generation space–time methods”, Computational Mechanics, 54 (2014) 193–211, 10.1007/s00466-014-0999-z
Times Cited in Web of Science Core Collection: 82, Times Cited in Scopus: 96
@ARTICLE{Takizawa14d, AUTHOR = {K.~Takizawa}, JOURNAL = {Computational Mechanics}, TITLE = {Computational Engineering Analysis with the New-Generation Space–Time Methods}, VOLUME = {54}, YEAR = {2014}, PAGES = {193–211}, DOI = {10.1007/s00466-014-0999-z} } Abstract:
This is an overview of the new directions we have taken the space-time (ST) methods in bringing solution and analysis to different classes of computationally challenging engineering problems. The classes of problems we have focused on include bio-inspired flapping-wing aerodynamics, wind-turbine aerodynamics, and cardiovascular fluid mechanics. The new directions for the ST methods include the variational multiscale version of the Deforming-Spatial- Domain/Stabilized ST method, using NURBS basis functions in temporal representation of the unknown variables and motion of the solid surfaces and fluid meshes, ST techniques with continuous representation in time, and ST interface-tracking with topology change. We describe the new directions and present examples of the challenging problems solved. © 2014 Springer-Verlag Berlin Heidelberg.

[53]

Y. Bazilevs, K. Takizawa, T.E. Tezduyar, M.-C. Hsu, N. Kostov, and S. McIntyre, “Aerodynamic and FSI analysis of wind turbines with the ALE-VMS and ST-VMS methods”, Archives of Computational Methods in Engineering, 21 (2014) 359–398, 10.1007/s11831-014-9119-7
Times Cited in Web of Science Core Collection: 92, Times Cited in Scopus: 109
@ARTICLE{Bazilevs14a, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar and Ming-Chen Hsu and N.~Kostov and S.~McIntyre}, JOURNAL = {Archives of Computational Methods in Engineering}, TITLE = {Aerodynamic and {FSI} Analysis of Wind Turbines with the {ALE-VMS} and {ST-VMS} Methods}, VOLUME = {21}, YEAR = {2014}, PAGES = {359–398}, DOI = {10.1007/s11831-014-9119-7} } Abstract:
We provide an overview of the aerodynamic and FSI analysis of wind turbines the first three authors’ teams carried out in recent years with the ALE-VMS and ST-VMS methods. The ALE-VMS method is the variational multiscale version of the Arbitrary Lagrangian–Eulerian (ALE) method. The VMS components are from the residual-based VMS (RBVMS) method. The ST-VMS method is the VMS version of the deforming-spatial-domain/stabilized space–time (DSD/SST) method. The techniques complementing these core methods include weak enforcement of the essential boundary conditions, NURBS-based isogeometric analysis, using NURBS basis functions in temporal representation of the rotor motion, mesh motion and also in remeshing, rotation representation with constant angular velocity, Kirchhoff–Love shell modeling of the rotor-blade structure, and full FSI coupling. The analysis cases include the aerodynamics of standalone wind-turbine rotors, wind-turbine rotor and tower, and the FSI that accounts for the deformation of the rotor blades. The specific wind turbines considered are NREL 5MW, NREL Phase VI and Micon 65/13M, all at full scale, and our analysis for NREL Phase VI and Micon 65/13M includes comparison with the experimental data.

[52]

K. Takizawa, Y. Bazilevs, T.E. Tezduyar, M.-C. Hsu, O. Øiseth, K.M. Mathisen, N. Kostov, and S. McIntyre, “Engineering analysis and design with ALE-VMS and space–time methods”, Archives of Computational Methods in Engineering, 21 (2014) 481–508, 10.1007/s11831-014-9113-0
Times Cited in Web of Science Core Collection: 91, Times Cited in Scopus: 104
@ARTICLE{Takizawa14c, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and Ming-Chen Hsu and O.~{\O}iseth and K. M.~Mathisen and N.~Kostov and S.~McIntyre}, JOURNAL = {Archives of Computational Methods in Engineering}, TITLE = {Engineering Analysis and Design with {ALE-VMS} and Space–Time Methods}, VOLUME = {21}, YEAR = {2014}, PAGES = {481–508}, DOI = {10.1007/s11831-014-9113-0} } Abstract:
Flow problems with moving boundaries and interfaces include fluid–structure interaction (FSI) and a number of other classes of problems, have an important place in engineering analysis and design, and offer some formidable computational challenges. Bringing solution and analysis to them motivated the Deforming-Spatial-Domain/Stabilized Space–Time (DSD/SST) method and also the variational multiscale version of the Arbitrary Lagrangian–Eulerian method (ALE-VMS). Since their inception, these two methods and their improved versions have been applied to a diverse set of challenging problems with a common core computational technology need. The classes of problems solved include free-surface and two-fluid flows, fluid–object and fluid–particle interaction, FSI, and flows with solid surfaces in fast, linear or rotational relative motion. Some of the most challenging FSI problems, including parachute FSI, wind-turbine FSI and arterial FSI, are being solved and analyzed with the DSD/SST and ALE-VMS methods as core technologies. Better accuracy and improved turbulence modeling were brought with the recently-introduced VMS version of the DSD/SST method, which is called DSD/SST-VMST (also ST-VMS). In specific classes of problems, such as parachute FSI, arterial FSI, ship hydrodynamics, fluid–object interaction, aerodynamics of flapping wings, and wind-turbine aerodynamics and FSI, the scope and accuracy of the FSI modeling were increased with the special ALE-VMS and ST FSI techniques targeting each of those classes of problems. This article provides an overview of the core ALE-VMS and ST FSI techniques, their recent versions, and the special ALE-VMS and ST FSI techniques. It also provides examples of challenging problems solved and analyzed in parachute FSI, arterial FSI, ship hydrodynamics, aerodynamics of flapping wings, wind-turbine aerodynamics, and bridge-deck aerodynamics and vortex-induced vibrations.

[51]

K. Takizawa, Y. Bazilevs, T.E. Tezduyar, C.C. Long, A.L. Marsden, and K. Schjodt, “ST and ALE-VMS methods for patient-specific cardiovascular fluid mechanics modeling”, Mathematical Models and Methods in Applied Sciences, 24 (2014) 2437–2486, 10.1142/S0218202514500250
Times Cited in Web of Science Core Collection: 95, Times Cited in Scopus: 108
@ARTICLE{Takizawa14b, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and C. C.~Long and A. L.~Marsden and K.~Schjodt}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {{ST} and {ALE-VMS} Methods for Patient-Specific Cardiovascular Fluid Mechanics Modeling}, VOLUME = {24}, NUMBER = {None}, YEAR = {2014}, PAGES = {2437–2486}, DOI = {10.1142/S0218202514500250} } Abstract:
This paper provides a review of the space-time (ST) and Arbitrary Lagrangian-Eulerian (ALE) techniques developed by the first three authors’ research teams for patient-specific cardiovascular fluid mechanics modeling, including fluid-structure interaction (FSI). The core methods are the ALE-based variational multiscale (ALE-VMS) method, the Deforming-Spatial-Domain/Stabilized ST formulation, and the stabilized ST FSI technique. A good number of special techniques targeting cardiovascular fluid mechanics have been developed to be used with the core methods. These include: (i) arterial-surface extraction and boundary condition techniques, (ii) techniques for using variable arterial wall thickness, (iii) methods for calculating an estimated zero-pressure arterial geometry, (iv) techniques for prestressing of the blood vessel wall, (v) mesh generation techniques for building layers of refined fluid mechanics mesh near the arterial walls, (vi) a special mapping technique for specifying the velocity profile at an inflow boundary with non-circular shape, (vii) a scaling technique for specifying a more realistic volumetric flow rate, (viii) techniques for the projection of fluid-structure interface stresses, (ix) a recipe for pre-FSI computations that improve the convergence of the FSI computations, (x) the Sequentially-Coupled Arterial FSI technique and its multiscale versions, (xi) techniques for calculation of the wall shear stress (WSS) and oscillatory shear index (OSI), (xii) methods for stent modeling and mesh generation, (xiii) methods for calculation of the particle residence time, and (xiv) methods for an estimated element-based zero-stress state for the artery. Here we provide an overview of the special techniques for WSS and OSI calculations, stent modeling and mesh generation, and calculation of the residence time with application to pulsatile ventricular assist device (PVAD). We provide references for some of the other special techniques. With results from earlier computations, we show how these core and special techniques work. © 2014 World Scientific Publishing Company.

[50]

K. Takizawa, T.E. Tezduyar, and N. Kostov, “Sequentially-coupled space–time FSI analysis of bio-inspired flapping-wing aerodynamics of an MAV”, Computational Mechanics, 54 (2014) 213–233, 10.1007/s00466-014-0980-x
Times Cited in Web of Science Core Collection: 86, Times Cited in Scopus: 99
@ARTICLE{Takizawa14a, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and N.~Kostov}, JOURNAL = {Computational Mechanics}, TITLE = {Sequentially-coupled space–time {FSI} analysis of bio-inspired flapping-wing aerodynamics of an {MAV}}, VOLUME = {54}, YEAR = {2014}, PAGES = {213–233}, DOI = {10.1007/s00466-014-0980-x} } Abstract:
We present a sequentially-coupled space-time (ST) computational fluid-structure interaction (FSI) analysis of flapping-wing aerodynamics of a micro aerial vehicle (MAV). The wing motion and deformation data, whether prescribed fully or partially, is from an actual locust, extracted from high-speed, multi-camera video recordings of the locust in a wind tunnel. The core computational FSI technology is based on the Deforming-Spatial-Domain/ Stabilized ST (DSD/SST) formulation. This is supplemented with using NURBS basis functions in temporal representation of the wing and mesh motion, and in remeshing. Here we use the version of the DSD/SST formulation derived in conjunction with the variational multiscale (VMS) method, and this version is called “DSD/SST-VMST.” The structural mechanics computations are based on the Kirchhoff-Love shell model. The sequential-coupling technique is applicable to some classes of FSI problems, especially those with temporally-periodic behavior. We show that it performs well in FSI computations of the flapping-wing aerodynamics we consider here. In addition to the straight-flight case, we analyze cases where the MAV body has rolling, pitching, or rolling and pitching motion. We study how all these influence the lift and thrust. © 2014 Springer-Verlag Berlin Heidelberg.

[49]

K. Takizawa, T.E. Tezduyar, A. Buscher, and S. Asada, “Space–time interface-tracking with topology change (ST-TC)”, Computational Mechanics, 54 (2014) 955–971, 10.1007/s00466-013-0935-7
Times Cited in Web of Science Core Collection: 106, Times Cited in Scopus: 122
@ARTICLE{Takizawa13e, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and A.~Buscher and S.~Asada}, JOURNAL = {Computational Mechanics}, TITLE = {Space–Time Interface-Tracking with Topology Change {(ST-TC)}}, VOLUME = {54}, YEAR = {2014}, PAGES = {955–971}, DOI = {10.1007/s00466-013-0935-7} } Abstract:
To address the computational challenges associated with contact between moving interfaces, such as those in cardiovascular fluid–structure interaction (FSI), parachute FSI, and flapping-wing aerodynamics, we introduce a space–time (ST) interface-tracking method that can deal with topology change (TC). In cardiovascular FSI, our primary target is heart valves. The method is a new version of the deforming-spatial-domain/stabilized space–time (DSD/SST) method, and we call it ST-TC. It includes a master–slave system that maintains the connectivity of the “parent” mesh when there is contact between the moving interfaces. It is an efficient, practical alternative to using unstructured ST meshes, but without giving up on the accurate representation of the interface or consistent representation of the interface motion. We explain the method with conceptual examples and present 2D test computations with models representative of the classes of problems we are targeting.

[48]

K. Takizawa, H. Takagi, T.E. Tezduyar, and R. Torii, “Estimation of element-based zero-stress state for arterial FSI computations”, Computational Mechanics, 54 (2014) 895–910, 10.1007/s00466-013-0919-7
Times Cited in Web of Science Core Collection: 42, Times Cited in Scopus: 46
@ARTICLE{Takizawa13d, AUTHOR = {K.~Takizawa and H.~Takagi and T. E.~Tezduyar and R.~Torii}, JOURNAL = {Computational Mechanics}, TITLE = {Estimation of Element-Based Zero-Stress State for Arterial {FSI} Computations}, VOLUME = {54}, YEAR = {2014}, PAGES = {895–910}, DOI = {10.1007/s00466-013-0919-7} } Abstract:
In patient-specific arterial fluid–structure interaction (FSI) computations the image-based arterial geometry comes from a configuration that is not stress-free. We present a method for estimation of element-based zero-stress (ZS) state. The method has three main components. (1) An iterative method, which starts with an initial guess for the ZS state, is used for computing the element-based ZS state such that when a given pressure load is applied, the image-based target shape is matched. (2) A method for straight-tube geometries with single and multiple layers is used for computing the element-based ZS state so that we match the given diameter and longitudinal stretch in the target configuration and the “opening angle.” (3) An element-based mapping between the arterial and straight-tube configurations is used for mapping from the arterial configuration to the straight-tube configuration, and for mapping the estimated ZS state of the straight tube back to the arterial configuration, to be used as the initial guess for the iterative method that matches the image-based target shape. We present a set of test computations to show how the method works.

[47]

K. Takizawa and T.E. Tezduyar, “Space–time computation techniques with continuous representation in time (ST-C)”, Computational Mechanics, 53 (2014) 91–99, 10.1007/s00466-013-0895-y
Times Cited in Web of Science Core Collection: 65, Times Cited in Scopus: 77
@ARTICLE{Takizawa13c, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Space–time computation techniques with continuous representation in time ({ST-C})}, VOLUME = {53}, YEAR = {2014}, PAGES = {91–99}, DOI = {10.1007/s00466-013-0895-y} } Abstract:
We introduce space-time computation techniques with continuous representation in time (ST-C), using temporal NURBS basis functions. This gives us a temporally smooth, NURBS-based solution, which is desirable in some cases, and a more efficient way of dealing with the computed data. We propose two versions of ST-C. In the first version, the smooth solution is extracted by projection from a solution computed with a different temporal representation, typically a discontinuous one. We use a successive projection technique with a small number of temporal NURBS basis functions at each projection, and therefore the extraction can take place as the solution with discontinuous temporal representation is being computed, without storing a large amount of time-history data. This version is not limited to solutions computed with ST techniques. In the second version, the solution with continuous temporal representation is computed directly by using a small number of temporal NURBS basis functions in the variational formulation associated with each time step. © 2013 Springer-Verlag Berlin Heidelberg.

[46]

K. Takizawa, T.E. Tezduyar, J. Boben, N. Kostov, C. Boswell, and A. Buscher, “Fluid–structure interaction modeling of clusters of spacecraft parachutes with modified geometric porosity”, Computational Mechanics, 52 (2013) 1351–1364, 10.1007/s00466-013-0880-5
Times Cited in Web of Science Core Collection: 93, Times Cited in Scopus: 106
@ARTICLE{Takizawa13b, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and J.~Boben and N.~Kostov and C.~Boswell and A.~Buscher}, JOURNAL = {Computational Mechanics}, TITLE = {Fluid–structure interaction modeling of clusters of spacecraft parachutes with modified geometric porosity}, VOLUME = {52}, YEAR = {2013}, PAGES = {1351–1364}, DOI = {10.1007/s00466-013-0880-5} } Abstract:
To increase aerodynamic performance, the geometric porosity of a ringsail spacecraft parachute canopy is sometimes increased, beyond the “rings” and “sails” with hundreds of “ring gaps” and “sail slits.” This creates extra computational challenges for fluid-structure interaction (FSI) modeling of clusters of such parachutes, beyond those created by the lightness of the canopy structure, geometric complexities of hundreds of gaps and slits, and the contact between the parachutes of the cluster. In FSI computation of parachutes with such “modified geometric porosity,” the flow through the “windows” created by the removal of the panels and the wider gaps created by the removal of the sails cannot be accurately modeled with the Homogenized Modeling of Geometric Porosity (HMGP), which was introduced to deal with the hundreds of gaps and slits. The flow needs to be actually resolved. All these computational challenges need to be addressed simultaneously in FSI modeling of clusters of spacecraft parachutes with modified geometric porosity. The core numerical technology is the Stabilized Space-Time FSI (SSTFSI) technique, and the contact between the parachutes is handled with the Surface-Edge-Node Contact Tracking (SENCT) technique. In the computations reported here, in addition to the SSTFSI and SENCT techniques and HMGP, we use the special techniques we have developed for removing the numerical spinning component of the parachute motion and for restoring the mesh integrity without a remesh. We present results for 2- and 3-parachute clusters with two different payload models. © 2013 Springer-Verlag Berlin Heidelberg.

[45]

K. Takizawa, T.E. Tezduyar, S. McIntyre, N. Kostov, R. Kolesar, and C. Habluetzel, “Space–time VMS computation of wind-turbine rotor and tower aerodynamics”, Computational Mechanics, 53 (2014) 1–15, 10.1007/s00466-013-0888-x
Times Cited in Web of Science Core Collection: 108, Times Cited in Scopus: 123
@ARTICLE{Takizawa13a, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and S.~McIntyre and N.~Kostov and R.~Kolesar and C.~Habluetzel}, JOURNAL = {Computational Mechanics}, TITLE = {Space–time {VMS} computation of wind-turbine rotor and tower aerodynamics}, VOLUME = {53}, YEAR = {2014}, PAGES = {1–15}, DOI = {10.1007/s00466-013-0888-x} } Abstract:
We present the space-time variational multiscale (ST-VMS) computation of wind-turbine rotor and tower aerodynamics. The rotor geometry is that of the NREL 5MW offshore baseline wind turbine. We compute with a given wind speed and a specified rotor speed. The computation is challenging because of the large Reynolds numbers and rotating turbulent flows, and computing the correct torque requires an accurate and meticulous numerical approach. The presence of the tower increases the computational challenge because of the fast, rotational relative motion between the rotor and tower. The ST-VMS method is the residual-based VMS version of the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) method, and is also called “DSD/SST-VMST” method (i.e., the version with the VMS turbulence model). In calculating the stabilization parameters embedded in the method, we are using a new element length definition for the diffusion-dominated limit. The DSD/SST method, which was introduced as a general-purpose moving-mesh method for computation of flows with moving interfaces, requires a mesh update method. Mesh update typically consists of moving the mesh for as long as possible and remeshing as needed. In the computations reported here, NURBS basis functions are used for the temporal representation of the rotor motion, enabling us to represent the circular paths associated with that motion exactly and specify a constant angular velocity corresponding to the invariant speeds along those paths. In addition, temporal NURBS basis functions are used in representation of the motion and deformation of the volume meshes computed and also in remeshing. We name this “ST/NURBS Mesh Update Method (STNMUM).” The STNMUM increases computational efficiency in terms of computer time and storage, and computational flexibility in terms of being able to change the time-step size of the computation. We use layers of thin elements near the blade surfaces, which undergo rigid-body motion with the rotor. We compare the results from computations with and without tower, and we also compare using NURBS and linear finite element basis functions in temporal representation of the mesh motion. © 2013 Springer-Verlag Berlin Heidelberg.

[44]

K. Takizawa and T.E. Tezduyar, “Bringing them down safely”, Mechanical Engineering, 134 (2012) 34–37
Times Cited in Web of Science Core Collection: 8
@ARTICLE{Takizawa12z, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mechanical Engineering}, TITLE = {Bringing them down safely}, VOLUME = {134}, NUMBER = {12}, YEAR = {2012}, PAGES = {34–37}, DOI = {None} }

[43]

K. Takizawa, B. Henicke, A. Puntel, N. Kostov, and T.E. Tezduyar, “Computer modeling techniques for flapping-wing aerodynamics of a locust”, Computers & Fluids, 85 (2013) 125–134, 10.1016/j.compfluid.2012.11.008
Times Cited in Web of Science Core Collection: 70, Times Cited in Scopus: 76
@ARTICLE{Takizawa12x, AUTHOR = {K.~Takizawa and B.~Henicke and A.~Puntel and N.~Kostov and T. E.~Tezduyar}, JOURNAL = {Computers \& Fluids}, TITLE = {Computer Modeling Techniques for Flapping-Wing Aerodynamics of a Locust}, VOLUME = {85}, YEAR = {2013}, PAGES = {125–134}, DOI = {10.1016/j.compfluid.2012.11.008} } Abstract:
We present an overview of the special computer modeling techniques we have developed recently for flapping-wing aerodynamics of a locust. The wing motion and deformation data is from an actual locust, extracted from high-speed, multi-camera video recordings of the locust in a wind tunnel. The special techniques have been developed around our core computational technique, which is the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation. Here we use the version of the DSD/SST formulation derived in conjunction with the variational multiscale (VMS) method, and this version is called “DSD/SST-VMST.” The special techniques are based on using, in the space-time flow computations, NURBS basis functions for the temporal representation of the motion and deformation of the locust wings. Temporal NURBS basis functions are used also in representation of the motion of the volume meshes computed and in remeshing. In this special-issue paper, we present a condensed version of the material from [1], concentrating on the flapping-motion modeling and computations, and also a temporal-order study from [2]. © 2012 Elsevier Ltd.

[42]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Challenges and directions in computational fluid–structure interaction”, Mathematical Models and Methods in Applied Sciences, 23 (2013) 215–221, 10.1142/S0218202513400010
Times Cited in Web of Science Core Collection: 101, Times Cited in Scopus: 113
@ARTICLE{Bazilevs13b, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Challenges and Directions in Computational Fluid–Structure Interaction}, VOLUME = {23}, NUMBER = {None}, YEAR = {2013}, PAGES = {215–221}, DOI = {10.1142/S0218202513400010} } Abstract:
In this lead paper of the special issue, we provide some comments on challenges and directions in computational fluid-structure interaction (FSI). We briefly discuss the significance of computational FSI methods, their components, moving-mesh and nonmoving-mesh methods, mesh moving and remeshing concepts, and FSI coupling techniques. © 2013 World Scientific Publishing Company.

[41]

K. Takizawa, K. Schjodt, A. Puntel, N. Kostov, and T.E. Tezduyar, “Patient-specific computational analysis of the influence of a stent on the unsteady flow in cerebral aneurysms”, Computational Mechanics, 51 (2013) 1061–1073, 10.1007/s00466-012-0790-y
Times Cited in Web of Science Core Collection: 78, Times Cited in Scopus: 94
@ARTICLE{Takizawa12w, AUTHOR = {K.~Takizawa and K.~Schjodt and A.~Puntel and N.~Kostov and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Patient-Specific Computational Analysis of the Influence of a Stent on the Unsteady Flow in Cerebral Aneurysms}, VOLUME = {51}, YEAR = {2013}, PAGES = {1061–1073}, DOI = {10.1007/s00466-012-0790-y} } Abstract:
We present a patient-specific computational analysis of the influence of a stent on the unsteady flow in cerebral aneurysms. The analysis is based on four different arterial models extracted form medical images, and the stent is placed across the neck of the aneurysm to reduce the flow circulation in the aneurysm. The core computational technique used in the analysis is the space-time (ST) version of the variational multiscale (VMS) method and is called “DSD/SST-VMST”. The special techniques developed for this class of cardiovascular fluid mechanics computations are used in conjunction with the DSD/SST-VMST technique. The special techniques include NURBS representation of the surface over which the stent model and mesh are built, mesh generation with a reasonable resolution across the width of the stent wire and with refined layers of mesh near the arterial and stent surfaces, modeling the double-stent case, and quantitative assessment of the flow circulation in the aneurysm. We provide a brief overview of the special techniques, compute the unsteady flow patterns in the aneurysm for the four arterial models, and investigate in each case how those patterns are influenced by the presence of single and double stents. © 2012 Springer-Verlag.

[40]

K. Takizawa, D. Montes, S. McIntyre, and T.E. Tezduyar, “Space–time VMS methods for modeling of incompressible flows at high Reynolds numbers”, Mathematical Models and Methods in Applied Sciences, 23 (2013) 223–248, 10.1142/s0218202513400022
Times Cited in Web of Science Core Collection: 70, Times Cited in Scopus: 84
@ARTICLE{Takizawa12g, AUTHOR = {K.~Takizawa and D.~Montes and S.~McIntyre and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Space–Time {VMS} Methods for Modeling of Incompressible Flows at High {R}eynolds Numbers}, VOLUME = {23}, NUMBER = {None}, YEAR = {2013}, PAGES = {223–248}, DOI = {10.1142/s0218202513400022} } Abstract:
Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation was developed for flow problems with moving interfaces and has been successfully applied to some of the most complex problems in that category. A new version of the DSD/SST method for incompressible flows, which has additional subgrid-scale representation features, is the space-time version of the residual-based variational multiscale (VMS) method. This new version, called DSD/SST-VMST and also Space-Time VMS (ST-VMS), provides a more comprehensive framework for the VMS method. We describe the ST-VMS method, including the embedded stabilization parameters, and assess its performance in computation of flow problems at high Reynolds numbers by comparing the results to experimental data. The computations, which include those with 3D airfoil geometries and spacecraft configurations, signal a promising future for the ST-VMS method. © 2013 World Scientific Publishing Company.

[39]

K. Takizawa, D. Montes, M. Fritze, S. McIntyre, J. Boben, and T.E. Tezduyar, “Methods for FSI modeling of spacecraft parachute dynamics and cover separation”, Mathematical Models and Methods in Applied Sciences, 23 (2013) 307–338, 10.1142/S0218202513400058
Times Cited in Web of Science Core Collection: 88, Times Cited in Scopus: 111
@ARTICLE{Takizawa12f, AUTHOR = {K.~Takizawa and D.~Montes and M.~Fritze and S.~McIntyre and J.~Boben and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Methods for {FSI} modeling of spacecraft parachute dynamics and cover separation}, VOLUME = {23}, NUMBER = {None}, YEAR = {2013}, PAGES = {307–338}, DOI = {10.1142/S0218202513400058} } Abstract:
Fluid-structure interaction (FSI) modeling of spacecraft parachutes involves a number of computational challenges beyond those encountered in a typical FSI problem. The stabilized space-time FSI (SSTFSI) technique serves as a robust and accurate core FSI method, and a number of special FSI methods address the computational challenges specific to spacecraft parachutes. Some spacecraft FSI problems involve even more specific computational challenges and require additional special methods. An example of that is the impulse ejection and parachute extraction of a protective cover used in a spacecraft. The computational challenges specific to this problem are related to the sudden changes in the parachute loads and sudden separation of the cover with very little initial clearance from the spacecraft. We describe the core and special FSI methods, and present the methods we use in FSI analysis of the parachute dynamics and cover separation, including the temporal NURBS representation in modeling the separation motion. © 2013 World Scientific Publishing Company.

[38]

K. Takizawa, M. Fritze, D. Montes, T. Spielman, and T.E. Tezduyar, “Fluid–structure interaction modeling of ringsail parachutes with disreefing and modified geometric porosity”, Computational Mechanics, 50 (2012) 835–854, 10.1007/s00466-012-0761-3
Times Cited in Web of Science Core Collection: 72, Times Cited in Scopus: 80
@ARTICLE{Takizawa12e, AUTHOR = {K.~Takizawa and M.~Fritze and D.~Montes and T.~Spielman and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Fluid–structure interaction modeling of ringsail parachutes with disreefing and modified geometric porosity}, VOLUME = {50}, YEAR = {2012}, PAGES = {835–854}, DOI = {10.1007/s00466-012-0761-3} } Abstract:
Fluid-structure interaction (FSI) modeling of parachutes poses a number of computational challenges. These include the lightness of the parachute canopy compared to the air masses involved in the parachute dynamics, in the case of ringsail parachutes the geometric porosity created by the construction of the canopy from “rings” and “sails” with hundreds of “ring gaps” and “sail slits,” in the case of parachute clusters the contact between the parachutes, and “disreefing” from one stage to another when the parachute is used in multiple stages. The Team for Advanced Flow Simulation and Modeling (Ta*AFSM) has been successfully addressing these computational challenges with the Stabilized Space-Time FSI (SSTFSI) technique, which was developed and improved over the years by the Ta*AFSM and serves as the core numerical technology, and a number of special techniques developed in conjunction with the SSTFSI technique. The quasi-direct and direct coupling techniques developed by the Ta*AFSM, which are applicable to cases with nonmatching fluid and structure meshes at the interface, yield more robust algorithms for FSI computations where the structure is light. The special technique used in dealing with the geometric complexities of the rings and sails is the homogenized modeling of geometric porosity (HMGP), which was developed and improved in recent years by the Ta*AFSM. The surface-edge-node contact tracking (SENCT) technique was introduced by the Ta*AFSM as a contact algorithm where the objective is to prevent the structural surfaces from coming closer than a minimum distance in an FSI computation. The recently-introduced conservative version of the SENCT technique is more robust and is now an essential technology in the parachute cluster computations carried out by the Ta*AFSM. As an additional computational challenge, the parachute canopy might, by design, have some of its panels and sails removed. In FSI computation of parachutes with such “modified geometric porosity,” the flow through the “windows” created by the removal of the panels and the wider gaps created by the removal of the sails cannot be accurately modeled with the HMGP and needs to be actually resolved during the FSI computation. In this paper we focus on parachute disreefing, including the disreefing of parachute clusters, and parachutes with modified geometric porosity, including the reefed stages of such parachutes. We describe the additional special techniques we have developed to address the challenges involved and report FSI computations for parachutes and parachute clusters with disreefing and modified geometric porosity. © 2012 Springer-Verlag.

[37]

K. Takizawa, K. Schjodt, A. Puntel, N. Kostov, and T.E. Tezduyar, “Patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent”, Computational Mechanics, 50 (2012) 675–686, 10.1007/s00466-012-0760-4
Times Cited in Web of Science Core Collection: 78, Times Cited in Scopus: 88
@ARTICLE{Takizawa12d, AUTHOR = {K.~Takizawa and K.~Schjodt and A.~Puntel and N.~Kostov and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent}, VOLUME = {50}, YEAR = {2012}, PAGES = {675–686}, DOI = {10.1007/s00466-012-0760-4} } Abstract:
We present the special arterial fluid mechanics techniques we have developed for patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent. These techniques are used in conjunction with the core computational technique, which is the space-time version of the variational multiscale (VMS) method and is called “DST/SST-VMST.” The special techniques include using NURBS for the spatial representation of the surface over which the stent mesh is built, mesh generation techniques for both the finite- and zero-thickness representations of the stent, techniques for generating refined layers of mesh near the arterial and stent surfaces, and models for representing double stent. We compute the unsteady flow patterns in the aneurysm and investigate how those patterns are influenced by the presence of single and double stents. We also compare the flow patterns obtained with the finite- and zero-thickness representations of the stent. © 2012 Springer-Verlag.

[36]

K. Takizawa, N. Kostov, A. Puntel, B. Henicke, and T.E. Tezduyar, “Space–time computational analysis of bio-inspired flapping-wing aerodynamics of a micro aerial vehicle”, Computational Mechanics, 50 (2012) 761–778, 10.1007/s00466-012-0758-y
Times Cited in Web of Science Core Collection: 98, Times Cited in Scopus: 108
@ARTICLE{Takizawa12c, AUTHOR = {K.~Takizawa and N.~Kostov and A.~Puntel and B.~Henicke and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Space–time computational analysis of bio-inspired flapping-wing aerodynamics of a micro aerial vehicle}, VOLUME = {50}, YEAR = {2012}, PAGES = {761–778}, DOI = {10.1007/s00466-012-0758-y} } Abstract:
We present a detailed computational analysis of bio-inspired flapping-wing aerodynamics of a micro aerial vehicle (MAV). The computational techniques used include the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation, which serves as the core computational technique. The DSD/SST formulation is a moving-mesh technique, and in the computations reported here we use the space-time version of the residual-based variational multiscale (VMS) method, which is called “DSD/ SST-VMST.” The motion and deformation of the wings are based on data extracted from the high-speed, multi-camera video recordings of a locust in a wind tunnel. A set of special space-time techniques are also used in the computations in conjunction with the DSD/SST method. The special techniques are based on using, in the space-time flow computations, NURBS basis functions for the temporal representation of the motion and deformation of the wings and for the mesh moving and remeshing. The computational analysis starts with the computation of the base case, and includes computations with increased temporal and spatial resolutions compared to the base case. In increasing the temporal resolution, we separately test increasing the temporal order, the number of temporal subdivisions, and the frequency of remeshing. In terms of the spatial resolution, we separately test increasing the wing-mesh refinement in the normal and tangential directions and changing the way node connectivities are handled at the wingtips. The computational analysis also includes using different combinations of wing configurations for the MAV and investigating the beneficial and disruptive interactions between the wings and the role of wing camber and twist. © 2012 Springer-Verlag.

[35]

K. Takizawa, B. Henicke, A. Puntel, N. Kostov, and T.E. Tezduyar, “Space–time techniques for computational aerodynamics modeling of flapping wings of an actual locust”, Computational Mechanics, 50 (2012) 743–760, 10.1007/s00466-012-0759-x
Times Cited in Web of Science Core Collection: 101, Times Cited in Scopus: 117
@ARTICLE{Takizawa12b, AUTHOR = {K.~Takizawa and B.~Henicke and A.~Puntel and N.~Kostov and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Space–Time Techniques for Computational Aerodynamics Modeling of Flapping Wings of an Actual Locust}, VOLUME = {50}, YEAR = {2012}, PAGES = {743–760}, DOI = {10.1007/s00466-012-0759-x} } Abstract:
We present the special space-time computational techniques we have introduced recently for computational aerodynamics modeling of flapping wings of an actual locust. These techniques have been designed to be used with the deforming-spatial-domain/stabilized space-time (DSD/SST) formulation, which is the core computational technique. The DSD/SST formulation was developed for flow problems with moving interfaces and was elevated to newer versions over the years, including the space-time version of the residual-based variational multiscale (VMS) method, which is called “DSD/SST-VMST” and used in the computations reported here. The special space-time techniques are based on using, in the space-time flow computations, NURBS basis functions for the temporal representation of the motion and deformation of the locust wings. The motion and deformation data is extracted from the high-speed, multi-camera video recordings of a locust in a wind tunnel. In addition, temporal NURBS basis functions are used in representation of the motion and deformation of the volume meshes computed and also in remeshing. These ingredients provide an accurate and efficient way of dealing with the wind tunnel data and the mesh. The computations demonstrate the effectiveness of the core and special space-time techniques in modeling the aerodynamics of flapping wings, with the wing motion and deformation coming from an actual locust. © 2012 Springer-Verlag.

[34]

Y. Bazilevs, M.-C. Hsu, K. Takizawa, and T.E. Tezduyar, “ALE-VMS and ST-VMS methods for computer modeling of wind-turbine rotor aerodynamics and fluid–structure interaction”, Mathematical Models and Methods in Applied Sciences, 22 (2012) 1230002, 10.1142/S0218202512300025
Times Cited in Web of Science Core Collection: 135, Times Cited in Scopus: 152
@ARTICLE{Bazilevs12a, AUTHOR = {Y.~Bazilevs and Ming-Chen Hsu and K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {{ALE-VMS} and {ST-VMS} Methods for Computer Modeling of Wind-Turbine Rotor Aerodynamics and Fluid–Structure Interaction}, VOLUME = {22}, NUMBER = {supp02}, YEAR = {2012}, PAGES = {1230002}, DOI = {10.1142/S0218202512300025} } Abstract:
We provide an overview of the Arbitrary LagrangianEulerian Variational Multiscale (ALE-VMS) and SpaceTime Variational Multiscale (ST-VMS) methods we have developed for computer modeling of wind-turbine rotor aerodynamics and fluidstructure interaction (FSI). The related techniques described include weak enforcement of the essential boundary conditions, KirchhoffLove shell modeling of the rotor-blade structure, NURBS-based isogeometric analysis, and full FSI coupling. We present results from application of these methods to computer modeling of NREL 5MW and NREL Phase VI wind-turbine rotors at full scale, including comparison with experimental data. © 2012 World Scientific Publishing Company.

[33]

K. Takizawa and T.E. Tezduyar, “Space–time fluid–structure interaction methods”, Mathematical Models and Methods in Applied Sciences, 22 (2012) 1230001, 10.1142/S0218202512300013
Times Cited in Web of Science Core Collection: 139, Times Cited in Scopus: 156
@ARTICLE{Takizawa12a, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mathematical Models and Methods in Applied Sciences}, TITLE = {Space–Time Fluid–Structure Interaction Methods}, VOLUME = {22}, NUMBER = {supp02}, YEAR = {2012}, PAGES = {1230001}, DOI = {10.1142/S0218202512300013} } Abstract:
Since its introduction in 1991 for computation of flow problems with moving boundaries and interfaces, the Deforming-Spatial-Domain/Stabilized SpaceTime (DSD/SST) formulation has been applied to a diverse set of challenging problems. The classes of problems computed include free-surface and two-fluid flows, fluidobject, fluidparticle and fluidstructure interaction (FSI), and flows with mechanical components in fast, linear or rotational relative motion. The DSD/SST formulation, as a core technology, is being used for some of the most challenging FSI problems, including parachute modeling and arterial FSI. Versions of the DSD/SST formulation introduced in recent years serve as lower-cost alternatives. More recent variational multiscale (VMS) version, which is called DSD/SST-VMST (and also ST-VMS), has brought better computational accuracy and serves as a reliable turbulence model. Special spacetime FSI techniques introduced for specific classes of problems, such as parachute modeling and arterial FSI, have increased the scope and accuracy of the FSI modeling in those classes of computations. This paper provides an overview of the core spacetime FSI technique, its recent versions, and the special spacetime FSI techniques. The paper includes test computations with the DSD/SST-VMST technique. © 2012 World Scientific Publishing Company.

[32]

K. Takizawa, Y. Bazilevs, and T.E. Tezduyar, “Space–time and ALE-VMS techniques for patient-specific cardiovascular fluid–structure interaction modeling”, Archives of Computational Methods in Engineering, 19 (2012) 171–225, 10.1007/s11831-012-9071-3
Times Cited in Web of Science Core Collection: 154, Times Cited in Scopus: 174
@ARTICLE{Takizawa11n, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar}, JOURNAL = {Archives of Computational Methods in Engineering}, TITLE = {Space–Time and {ALE-VMS} Techniques for Patient-Specific Cardiovascular Fluid–Structure Interaction Modeling}, VOLUME = {19}, YEAR = {2012}, PAGES = {171–225}, DOI = {10.1007/s11831-012-9071-3} } Abstract:
This is an extensive overview of the core and special space-time and Arbitrary Lagrangian-Eulerian (ALE) techniques developed by the authors’ research teams for patient-specific cardiovascular fluid-structure interaction (FSI) modeling. The core techniques are the ALE-based variational multiscale (ALE-VMS) method, the Deforming-Spatial-Domain/Stabilized Space-Time formulation, and the stabilized space-time FSI technique. The special techniques include methods for calculating an estimated zero-pressure arterial geometry, prestressing of the blood vessel wall, a special mapping technique for specifying the velocity profile at an inflow boundary with non-circular shape, techniques for using variable arterial wall thickness, mesh generation techniques for building layers of refined fluid mechanics mesh near the arterial walls, a recipe for pre-FSI computations that improve the convergence of the FSI computations, the Sequentially-Coupled Arterial FSI technique and its multiscale versions, techniques for the projection of fluid-structure interface stresses, calculation of the wall shear stress and oscillatory shear index, arterial-surface extraction and boundary condition techniques, and a scaling technique for specifying a more realistic volumetric flow rate. With results from earlier computations, we show how these core and special FSI techniques work in patient-specific cardiovascular simulations. © 2012 CIMNE, Barcelona, Spain.

[31]

K. Takizawa and T.E. Tezduyar, “Computational methods for parachute fluid–structure interactions”, Archives of Computational Methods in Engineering, 19 (2012) 125–169, 10.1007/s11831-012-9070-4
Times Cited in Web of Science Core Collection: 129, Times Cited in Scopus: 151
@ARTICLE{Takizawa11m, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Archives of Computational Methods in Engineering}, TITLE = {Computational Methods for Parachute Fluid–Structure Interactions}, VOLUME = {19}, YEAR = {2012}, PAGES = {125–169}, DOI = {10.1007/s11831-012-9070-4} } Abstract:
The computational challenges posed by fluid-structure interaction (FSI) modeling of parachutes include the lightness of the parachute canopy compared to the air masses involved in the parachute dynamics, in the case of “ringsail” parachutes the geometric complexities created by the construction of the canopy from “rings” and “sails” with hundreds of ring “gaps” and sail “slits”, and in the case of parachute clusters the contact between the parachutes. The Team for Advanced Flow Simulation and Modeling (T*AFSM) has successfully addressed these computational challenges with the Stabilized Space-Time FSI (SSTFSI) technique, which was developed and improved over the years by the T*AFSM and serves as the core numerical technology, and a number of special techniques developed in conjunction with the SSTFSI technique. The quasi-direct and direct coupling techniques developed by the T*AFSM, which are applicable to cases with incompatible fluid and structure meshes at the interface, yield more robust algorithms for FSI computations where the structure is light and therefore more sensitive to the variations in the fluid dynamics forces. The special technique used in dealing with the geometric complexities of the rings and sails is the Homogenized Modeling of Geometric Porosity, which was developed and improved in recent years by the T*AFSM. The Surface-Edge-Node Contact Tracking (SENCT) technique was introduced by the T*AFSM as a contact algorithm where the objective is to prevent the structural surfaces from coming closer than a minimum distance in an FSI computation. The recently-introduced conservative version of the SENCT technique is more robust and is now an essential technology in the parachute cluster computations carried out by the T*AFSM. We provide an overview of the core and special techniques developed by the T*AFSM, present single-parachute FSI computations carried out for design-parameter studies, and report FSI computation and dynamical analysis of two-parachute clusters. © 2012 CIMNE, Barcelona, Spain.

[30]

K. Takizawa, B. Henicke, A. Puntel, T. Spielman, and T.E. Tezduyar, “Space–time computational techniques for the aerodynamics of flapping wings”, Journal of Applied Mechanics, 79 (2012) 010903, 10.1115/1.4005073
Times Cited in Web of Science Core Collection: 101, Times Cited in Scopus: 125
@ARTICLE{Takizawa11e, AUTHOR = {K.~Takizawa and B.~Henicke and A.~Puntel and T.~Spielman and T. E.~Tezduyar}, JOURNAL = {Journal of Applied Mechanics}, TITLE = {Space–time computational techniques for the aerodynamics of flapping wings}, VOLUME = {79}, YEAR = {2012}, PAGES = {010903}, DOI = {10.1115/1.4005073} } Abstract:
We present the special space-time computational techniques we have introduced recently for computation of flow problems with moving and deforming solid surfaces. The techniques have been designed in the context of the deforming-spatial-domain/stabilized space-time formulation, which was developed by the Team for Advanced Flow Simulation and Modeling for computation of flow problems with moving boundaries and interfaces. The special space-time techniques are based on using, in the space-time flow computations, non-uniform rational B-splines (NURBS) basis functions for the temporal representation of the motion and deformation of the solid surfaces and also for the motion and deformation of the volume meshes computed. This provides a better temporal representation of the solid surfaces and a more effective way of handling the volume-mesh motion. We apply these techniques to computation of the aerodynamics of flapping wings, specifically locust wings, where the prescribed motion and deformation of the wings are based on digital data extracted from the videos of the locust in a wind tunnel. We report results from the preliminary computations. © 2012 American Society of Mechanical Engineers.

[29]

K. Takizawa, T. Brummer, T.E. Tezduyar, and P.R. Chen, “A comparative study based on patient-specific fluid–structure interaction modeling of cerebral aneurysms”, Journal of Applied Mechanics, 79 (2012) 010908, 10.1115/1.4005071
Times Cited in Web of Science Core Collection: 34, Times Cited in Scopus: 40
@ARTICLE{Takizawa11d, AUTHOR = {K.~Takizawa and T.~Brummer and T. E.~Tezduyar and P. R.~Chen}, JOURNAL = {Journal of Applied Mechanics}, TITLE = {A comparative study based on patient-specific fluid–structure interaction modeling of cerebral aneurysms}, VOLUME = {79}, YEAR = {2012}, PAGES = {010908}, DOI = {10.1115/1.4005071} } Abstract:
We present an extensive comparative study based on patient-specific fluid-structure interaction (FSI) modeling of cerebral aneurysms. We consider a total of ten cases, at three different locations, half of which ruptured. We use the stabilized space-time FSI technique developed by the Team for Advanced Flow Simulation and Modeling (T AFSM), together with a number of special techniques targeting arterial FSI modeling, which were also developed by the T AFSM. What we look at in our comparisons includes the wall shear stress, oscillatory shear index and the arterial-wall stress and stretch. We also investigate how simpler approaches to computer modeling of cerebral aneurysms perform compared to FSI modeling. © 2012 American Society of Mechanical Engineers.

[28]

K. Takizawa, T. Spielman, C. Moorman, and T.E. Tezduyar, “Fluid–structure interaction modeling of spacecraft parachutes for simulation-based design”, Journal of Applied Mechanics, 79 (2012) 010907, 10.1115/1.4005070
Times Cited in Web of Science Core Collection: 32, Times Cited in Scopus: 47
@ARTICLE{Takizawa11c, AUTHOR = {K.~Takizawa and T.~Spielman and C.~Moorman and T. E.~Tezduyar}, JOURNAL = {Journal of Applied Mechanics}, TITLE = {Fluid–structure interaction modeling of spacecraft parachutes for simulation-based design}, VOLUME = {79}, YEAR = {2012}, PAGES = {010907}, DOI = {10.1115/1.4005070} } Abstract:
Even though computer modeling of spacecraft parachutes involves a number of numerical challenges, advanced techniques developed in recent years for fluid-structure interaction (FSI) modeling in general and for parachute FSI modeling specifically have made simulation-based design studies possible. In this paper we focus on such studies for a single main parachute to be used with the Orion spacecraft. Although these large parachutes are typically used in clusters of two or three parachutes, studies for a single parachute can still provide valuable information for performance analysis and design and can be rather extensive. The major challenges in computer modeling of a single spacecraft parachute are the FSI between the air and the parachute canopy and the geometric complexities created by the construction of the parachute from rings and sails with hundreds of gaps and slits. The Team for Advanced Flow Simulation and Modeling has successfully addressed the computational challenges related to the FSI and geometric complexities, and has also been devising special procedures as needed for specific design parameter studies. In this paper we present parametric studies based on the suspension line length, canopy loading, and the length of the overinflation control line. © 2012 American Society of Mechanical Engineers.

[27]

M. Manguoglu, K. Takizawa, A.H. Sameh, and T.E. Tezduyar, “A parallel sparse algorithm targeting arterial fluid mechanics computations”, Computational Mechanics, 48 (2011) 377–384, 10.1007/s00466-011-0619-0
Times Cited in Web of Science Core Collection: 28, Times Cited in Scopus: 31
@ARTICLE{Manguoglu11a, AUTHOR = {M.~Manguoglu and K.~Takizawa and A. H.~Sameh and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {A parallel sparse algorithm targeting arterial fluid mechanics computations}, VOLUME = {48}, YEAR = {2011}, PAGES = {377–384}, DOI = {10.1007/s00466-011-0619-0} } Abstract:
Iterative solution of large sparse nonsymmetric linear equation systems is one of the numerical challenges in arterial fluid-structure interaction computations. This is because the fluid mechanics parts of the fluid + structure block of the equation system that needs to be solved at every nonlinear iteration of each time step corresponds to incompressible flow, the computational domains include slender parts, and accurate wall shear stress calculations require boundary layer mesh refinement near the arterial walls. We propose a hybrid parallel sparse algorithm, domain-decomposing parallel solver (DDPS), to address this challenge. As the test case, we use a fluid mechanics equation system generated by starting with an arterial shape and flow field coming from an FSI computation and performing two time steps of fluid mechanics computation with a prescribed arterial shape change, also coming from the FSI computation. We show how the DDPS algorithm performs in solving the equation system and demonstrate the scalability of the algorithm. © 2011 Springer-Verlag.

[26]

K. Takizawa, B. Henicke, D. Montes, T.E. Tezduyar, M.-C. Hsu, and Y. Bazilevs, “Numerical-performance studies for the stabilized space–time computation of wind-turbine rotor aerodynamics”, Computational Mechanics, 48 (2011) 647–657, 10.1007/s00466-011-0614-5
Times Cited in Web of Science Core Collection: 106, Times Cited in Scopus: 126
@ARTICLE{Takizawa11f, AUTHOR = {K.~Takizawa and B.~Henicke and D.~Montes and T. E.~Tezduyar and Ming-Chen Hsu and Y.~Bazilevs}, JOURNAL = {Computational Mechanics}, TITLE = {Numerical-Performance Studies for the Stabilized Space–Time Computation of Wind-Turbine Rotor Aerodynamics}, VOLUME = {48}, YEAR = {2011}, PAGES = {647–657}, DOI = {10.1007/s00466-011-0614-5} } Abstract:
We present our numerical-performance studies for 3D wind-turbine rotor aerodynamics computation with the deforming-spatial-domain/stabilized space-time (DSD/SST) formulation. The computation is challenging because of the large Reynolds numbers and rotating turbulent flows, and computing the correct torque requires an accurate and meticulous numerical approach. As the test case, we use the NREL 5MW offshore baseline wind-turbine rotor. We compute the problem with both the original version of the DSD/SST formulation and the version with an advanced turbulence model. The DSD/SST formulation with the turbulence model is a recently-introduced space-time version of the residual-based variational multiscale method. We include in our comparison as reference solution the results obtained with the residual-based variational multiscale Arbitrary Lagrangian-Eulerian method using NURBS for spatial discretization. We test different levels of mesh refinement and different definitions for the stabilization parameter embedded in the “least squares on incompressibility constraint” stabilization. We compare the torque values obtained. © 2011 Springer-Verlag.

[25]

K. Takizawa, T. Spielman, and T.E. Tezduyar, “Space–time FSI modeling and dynamical analysis of spacecraft parachutes and parachute clusters”, Computational Mechanics, 48 (2011) 345–364, 10.1007/s00466-011-0590-9
Times Cited in Web of Science Core Collection: 72, Times Cited in Scopus: 82
@ARTICLE{Takizawa11b, AUTHOR = {K.~Takizawa and T.~Spielman and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Space–time {FSI} modeling and dynamical analysis of spacecraft parachutes and parachute clusters}, VOLUME = {48}, YEAR = {2011}, PAGES = {345–364}, DOI = {10.1007/s00466-011-0590-9} } Abstract:
Computer modeling of spacecraft parachutes, which are quite often used in clusters of two or three large parachutes, involves fluid-structure interaction (FSI) between the parachute canopy and the air, geometric complexities created by the construction of the parachute from “rings” and “sails” with hundreds of gaps and slits, and the contact between the parachutes. The Team for Advanced Flow Simulation and Modeling (T*AFSM) has successfully addressed the computational challenges related to the FSI and geometric complexities, and recently started addressing the challenges related to the contact between the parachutes of a cluster. The core numerical technology is the stabilized space-time FSI technique developed and improved over the years by the (T*AFSM) . The special technique used in dealing with the geometric complexities is the Homogenized Modeling of Geometric Porosity, which was also developed and improved in recent years by the (T*AFSM) . In this paper we describe the technique developed by the (T*AFSM) for modeling, in the context of an FSI problem, the contact between two structural surfaces. We show how we use this technique in dealing with the contact between parachutes. We present the results obtained with the FSI computation of parachute clusters, the related dynamical analysis, and a special decomposition technique for parachute descent speed to make that analysis more informative. We also present a special technique for extracting from a parachute FSI computation model parameters, such as added mass, that can be used in fast, approximate engineering analysis models for parachute dynamics. © 2011 Springer-Verlag.

[24]

K. Takizawa, B. Henicke, T.E. Tezduyar, M.-C. Hsu, and Y. Bazilevs, “Stabilized space–time computation of wind-turbine rotor aerodynamics”, Computational Mechanics, 48 (2011) 333–344, 10.1007/s00466-011-0589-2
Times Cited in Web of Science Core Collection: 109, Times Cited in Scopus: 123
@ARTICLE{Takizawa11a, AUTHOR = {K.~Takizawa and B.~Henicke and T. E.~Tezduyar and Ming-Chen Hsu and Y.~Bazilevs}, JOURNAL = {Computational Mechanics}, TITLE = {Stabilized Space–Time Computation of Wind-Turbine Rotor Aerodynamics}, VOLUME = {48}, YEAR = {2011}, PAGES = {333–344}, DOI = {10.1007/s00466-011-0589-2} } Abstract:
We show how we use the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation for accurate 3D computation of the aerodynamics of a wind-turbine rotor. As the test case, we use the NREL 5MW offshore baseline wind-turbine rotor. This class of computational problems are rather challenging, because they involve large Reynolds numbers and rotating turbulent flows, and computing the correct torque requires an accurate and meticulous numerical approach. We compute the problem with both the original version of the DSD/SST formulation and a recently introduced version with an advanced turbulence model. The DSD/SST formulation with the advanced turbulence model is a space-time version of the residual-based variational multiscale method. We compare our results to those reported recently, which were obtained with the residual-based variational multiscale Arbitrary Lagrangian-Eulerian method using NURBS for spatial discretization and which we take as the reference solution. While the original DSD/SST formulation yields torque values not far from the reference solution, the DSD/SST formulation with the variational multiscale turbulence model yields torque values very close to the reference solution. © 2011 Springer-Verlag.

[23]

K. Takizawa and T.E. Tezduyar, “Multiscale space–time fluid–structure interaction techniques”, Computational Mechanics, 48 (2011) 247–267, 10.1007/s00466-011-0571-z
Times Cited in Web of Science Core Collection: 211, Times Cited in Scopus: 242
@ARTICLE{Takizawa10b, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Multiscale Space–Time Fluid–Structure Interaction Techniques}, VOLUME = {48}, YEAR = {2011}, PAGES = {247–267}, DOI = {10.1007/s00466-011-0571-z} } Abstract:
We present the multiscale space-time techniques we have developed for fluid-structure interaction (FSI) computations. Some of these techniques are multiscale in the way the time integration is performed (i.e. temporally multiscale), some are multiscale in the way the spatial discretization is done (i.e. spatially multiscale), and some are in the context of the sequentially-coupled FSI (SCFSI) techniques developed by the Team for Advanced Flow Simulation and Modeling T AFSM . In the multiscale SCFSI technique, the FSI computational effort is reduced at the stage we do not need it and the accuracy of the fluid mechanics (or structural mechanics) computation is increased at the stage we need accurate, detailed flow (or structure) computation. As ways of increasing the computational accuracy when or where needed, and beyond just increasing the mesh refinement or decreasing the time-step size, we propose switching to more accurate versions of the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation, using more polynomial power for the basis functions of the spatial discretization or time integration, and using an advanced turbulence model. Specifically, for more polynomial power in time integration, we propose to use NURBS, and as an advanced turbulence model to be used with the DSD/SST formulation, we introduce a space-time version of the residual-based variational multiscale method. We present a number of test computations showing the performance of the multiscale space-time techniques we are proposing. We also present a stability and accuracy analysis for the higher-accuracy versions of the DSD/SST formulation. © 2011 Springer-Verlag.

[22]

T.E. Tezduyar, K. Takizawa, T. Brummer, and P.R. Chen, “Space–time fluid–structure interaction modeling of patient-specific cerebral aneurysms”, International Journal for Numerical Methods in Biomedical Engineering, 27 (2011) 1665–1710, 10.1002/cnm.1433
Times Cited in Web of Science Core Collection: 80, Times Cited in Scopus: 90
@ARTICLE{Tezduyar10b, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and T.~Brummer and P. R.~Chen}, JOURNAL = {International Journal for Numerical Methods in Biomedical Engineering}, TITLE = {Space–Time Fluid–Structure Interaction Modeling of Patient-Specific Cerebral Aneurysms}, VOLUME = {27}, YEAR = {2011}, PAGES = {1665–1710}, DOI = {10.1002/cnm.1433} } Abstract:
We provide an extensive overview of the core and special techniques developed earlier by the Team for Advanced Flow Simulation and Modeling (T{black star}AFSM) for space-time fluid-structure interaction (FSI) modeling of patient-specific cerebral aneurysms. The core FSI techniques are the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation and the stabilized space-time FSI (SSTFSI) technique. The special techniques include techniques for calculating an estimated zero-pressure (EZP) arterial geometry, a special mapping technique for specifying the velocity profile at an inflow boundary with non-circular shape, techniques for using variable arterial wall thickness, mesh generation techniques for building layers of refined fluid mechanics mesh near the arterial walls, a recipe for pre-FSI computations that improve the convergence of the FSI computations, the Sequentially-Coupled Arterial FSI (SCAFSI) technique and its multiscale versions, techniques for the projection of fluid-structure interface stresses, calculation of the wall shear stress (WSS) and calculation of the oscillatory shear index (OSI) and arterial-surface extraction and boundary condition techniques. We show how these techniques work with results from earlier computations. We also describe the arterial FSI techniques developed and implemented recently by the T{black star}AFSM and present a sample from a wide set of patient-specific cerebral-aneurysm models we computed recently. © 2011 John Wiley & Sons, Ltd.

[21]

M. Manguoglu, K. Takizawa, A.H. Sameh, and T.E. Tezduyar, “Nested and parallel sparse algorithms for arterial fluid mechanics computations with boundary layer mesh refinement”, International Journal for Numerical Methods in Fluids, 65 (2011) 135–149, 10.1002/fld.2415
Times Cited in Web of Science Core Collection: 40, Times Cited in Scopus: 42
@ARTICLE{Manguoglu10a, AUTHOR = {M.~Manguoglu and K.~Takizawa and A. H.~Sameh and T. E.~Tezduyar}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {Nested and Parallel Sparse Algorithms for Arterial Fluid Mechanics Computations with Boundary Layer Mesh Refinement}, VOLUME = {65}, YEAR = {2011}, PAGES = {135–149}, DOI = {10.1002/fld.2415} } Abstract:
Arterial fluid-structure interaction (FSI) computations involve a number of numerical challenges. Because blood flow is incompressible, iterative solution of the fluid mechanics part of the linear equation system at every nonlinear iteration of each time step is one of those challenges, especially for computations over slender domains and in the presence of boundary layer mesh refinement. In this paper we address that challenge. As test cases, we use equation systems from stabilized finite element computation of a bifurcating middle cerebral artery segment with aneurysm, with thin layers of elements near the arterial wall. We show how the preconditioning techniques, we propose for solving these large sparse nonsymmetric systems, perform at different time steps of the computation over a cardiac cycle. We also present a new hybrid parallel sparse linear system solver ‘DD-Spike’ and demonstrate its scalability. © 2010 John Wiley & Sons, Ltd.

[20]

Y. Bazilevs, M.-C. Hsu, I. Akkerman, S. Wright, K. Takizawa, B. Henicke, T. Spielman, and T.E. Tezduyar, “3D simulation of wind turbine rotors at full scale. Part I: Geometry modeling and aerodynamics”, International Journal for Numerical Methods in Fluids, 65 (2011) 207–235, 10.1002/fld.2400
Times Cited in Web of Science Core Collection: 262, Times Cited in Scopus: 332
@ARTICLE{Bazilevs10a, AUTHOR = {Y.~Bazilevs and Ming-Chen Hsu and I.~Akkerman and S.~Wright and K.~Takizawa and B.~Henicke and T.~Spielman and T. E.~Tezduyar}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {3{D} Simulation of Wind Turbine Rotors at Full Scale. {P}art {I}: {G}eometry Modeling and Aerodynamics}, VOLUME = {65}, YEAR = {2011}, PAGES = {207–235}, DOI = {10.1002/fld.2400} } Abstract:
In this two-part paper we present a collection of numerical methods combined into a single framework, which has the potential for a successful application to wind turbine rotor modeling and simulation. In Part 1 of this paper we focus on: 1. The basics of geometry modeling and analysis-suitable geometry construction for wind turbine rotors; 2. The fluid mechanics formulation and its suitability and accuracy for rotating turbulent flows; 3. The coupling of air flow and a rotating rigid body. In Part 2 we focus on the structural discretization for wind turbine blades and the details of the fluid-structure interaction computational procedures. The methods developed are applied to the simulation of the NREL 5MW offshore baseline wind turbine rotor. The simulations are performed at realistic wind velocity and rotor speed conditions and at full spatial scale. Validation against published data is presented and possibilities of the newly developed computational framework are illustrated on several examples. © 2010 John Wiley & Sons, Ltd.

[19]

K. Takizawa, S. Wright, C. Moorman, and T.E. Tezduyar, “Fluid–structure interaction modeling of parachute clusters”, International Journal for Numerical Methods in Fluids, 65 (2011) 286–307, 10.1002/fld.2359
Times Cited in Web of Science Core Collection: 86, Times Cited in Scopus: 94
@ARTICLE{Takizawa10a, AUTHOR = {K.~Takizawa and S.~Wright and C.~Moorman and T. E.~Tezduyar}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {Fluid–Structure Interaction Modeling of Parachute Clusters}, VOLUME = {65}, YEAR = {2011}, PAGES = {286–307}, DOI = {10.1002/fld.2359} } Abstract:
We address some of the computational challenges involved in fluid-structure interaction (FSI) modeling of clusters of ringsail parachutes. The geometric complexity created by the construction of the parachute from ‘rings’ and ‘sails’ with hundreds of gaps and slits makes this class of FSI modeling inherently challenging. There is still much room for advancing the computational technology for FSI modeling of a single raingsail parachute, such as improving the Homogenized Modeling of Geometric Porosity (HMGP) and developing special techniques for computing the reefed stages of the parachute and its disreefing. While we continue working on that, we are also developing special techniques targeting cluster modeling, so that the computational technology goes beyond the single parachute and the challenges specific to parachute clusters are addressed. The rotational-periodicity technique we describe here is one of such special techniques, and we use that for computing good starting conditions for FSI modeling of parachute clusters. In addition to reporting our preliminary FSI computations for parachute clusters, we present results from those starting-condition computations. In the category of more fundamental computational technologies, we discuss how we are improving the HMGP by increasing the resolution of the fluid mechanics mesh used in the HMGP computation and also by increasing the number of gores used. Also in that category, we describe how we use the multiscale sequentially coupled FSI techniques to improve the accuracy in computing the structural stresses in parts of the structure where we want to report more accurate values. All these special techniques are used in conjunction with the Stabilized Space-Time Fluid-Structure Interaction (SSTFSI) technique. Therefore, we also present in this paper a brief stability and accuracy analysis for the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation, which is the core numerical technology of the SSTFSI technique. © 2010 John Wiley & Sons, Ltd.

[18]

K. Takizawa, C. Moorman, S. Wright, J. Purdue, T. McPhail, P.R. Chen, J. Warren, and T.E. Tezduyar, “Patient-specific arterial fluid–structure interaction modeling of cerebral aneurysms”, International Journal for Numerical Methods in Fluids, 65 (2011) 308–323, 10.1002/fld.2360
Times Cited in Web of Science Core Collection: 74, Times Cited in Scopus: 79
@ARTICLE{Takizawa09f, AUTHOR = {K.~Takizawa and C.~Moorman and S.~Wright and J.~Purdue and T.~McPhail and P. R.~Chen and J.~Warren and T. E.~Tezduyar}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {Patient-Specific Arterial Fluid–Structure Interaction Modeling of Cerebral Aneurysms}, VOLUME = {65}, YEAR = {2011}, PAGES = {308–323}, DOI = {10.1002/fld.2360} } Abstract:
We address the computational challenges related to the extraction of the arterial-lumen geometry, mesh generation and starting-point determination in the computation of arterial fluid-structure interactions (FSI) with patient-specific data. The methods we propose here to address those challenges include techniques for constructing suitable cutting planes at the artery inlets and outlets and specifying on those planes proper boundary conditions for the fluid mechanics, structural mechanics and fluid mesh motion and a technique for the improved calculation of an estimated zero-pressure arterial geometry. We use the stabilized space-time FSI technique, together with a number of special techniques recently developed for arterial FSI. We focus on three patient-specific cerebral artery segments with aneurysm, where the lumen geometries are extracted from 3D rotational angiography. © 2010 John Wiley & Sons, Ltd.

[17]

K. Takizawa, C. Moorman, S. Wright, T. Spielman, and T.E. Tezduyar, “Fluid–structure interaction modeling and performance analysis of the Orion spacecraft parachutes”, International Journal for Numerical Methods in Fluids, 65 (2011) 271–285, 10.1002/fld.2348
Times Cited in Web of Science Core Collection: 62, Times Cited in Scopus: 73
@ARTICLE{Takizawa09e, AUTHOR = {K.~Takizawa and C.~Moorman and S.~Wright and T.~Spielman and T. E.~Tezduyar}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {Fluid–Structure Interaction Modeling and Performance Analysis of the {O}rion Spacecraft Parachutes}, VOLUME = {65}, YEAR = {2011}, PAGES = {271–285}, DOI = {10.1002/fld.2348} } Abstract:
We focus on fluid-structure interaction (FSI) modeling and performance analysis of the ringsail parachutes to be used with the Orion spacecraft. We address the computational challenges with the latest techniques developed by the T-AFSM (Team for Advanced Flow Simulation and Modeling) in conjunction with the SSTFSI (Stabilized Space-Time Fluid-Structure Interaction) technique. The challenges involved in FSI modeling include the geometric porosity of the ringsail parachutes with ring gaps and sail slits. We investigate the performance of three possible design configurations of the parachute canopy. We also describe the techniques developed recently for building a consistent starting condition for the FSI computations, discuss rotational periodicity techniques for improving the geometric-porosity modeling, and introduce a new version of the HMGP (Homogenized Modeling of Geometric Porosity). © 2010 John Wiley & Sons, Ltd.

[16]

T.E. Tezduyar, K. Takizawa, C. Moorman, S. Wright, and J. Christopher, “Space–time finite element computation of complex fluid–structure interactions”, International Journal for Numerical Methods in Fluids, 64 (2010) 1201–1218, 10.1002/fld.2221
Times Cited in Web of Science Core Collection: 143, Times Cited in Scopus: 161
@ARTICLE{Tezduyar09f, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and C.~Moorman and S.~Wright and J.~Christopher}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {Space–Time Finite Element Computation of Complex Fluid–Structure Interactions}, VOLUME = {64}, YEAR = {2010}, PAGES = {1201–1218}, DOI = {10.1002/fld.2221} } Abstract:
New special fluid-structure interaction (FSI) techniques, supplementing the ones developed earlier, are employed with the Stabilized Space-Time FSI (SSTFSI) technique. The new special techniques include improved ways of calculating the equivalent fabric porosity in Homogenized Modeling of Geometric Porosity (HMGP), improved ways of building a starting point in FSI computations, ways of accounting for fluid forces acting on structural components that are not expected to influence the flow, adaptive HMGP, and multiscale sequentially coupled FSI techniques. While FSI modeling of complex parachutes was the motivation behind developing some of these techniques, they are also applicable to other classes of complex FSI problems. We also present new ideas to increase the scope of our FSI and CFD techniques. © 2009 John Wiley & Sons, Ltd.

[15]

K. Takizawa, C. Moorman, S. Wright, J. Christopher, and T.E. Tezduyar, “Wall shear stress calculations in space–time finite element computation of arterial fluid–structure interactions”, Computational Mechanics, 46 (2010) 31–41, 10.1007/s00466-009-0425-0
Times Cited in Web of Science Core Collection: 83, Times Cited in Scopus: 93
@ARTICLE{Takizawa09d, AUTHOR = {K.~Takizawa and C.~Moorman and S.~Wright and J.~Christopher and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Wall Shear Stress Calculations in Space–Time Finite Element Computation of Arterial Fluid–Structure Interactions}, VOLUME = {46}, YEAR = {2010}, PAGES = {31–41}, DOI = {10.1007/s00466-009-0425-0} } Abstract:
The stabilized space-time fluid-structure interaction (SSTFSI) technique was applied to arterial FSI problems soon after its development by the Team for Advanced Flow Simulation and Modeling. The SSTFSI technique is based on the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation and is supplemented with a number of special techniques developed for arterial FSI. The special techniques developed in the recent past include a recipe for pre-FSI computations that improve the convergence of the FSI computations, using an estimated zero-pressure arterial geometry, Sequentially Coupled Arterial FSI technique, using layers of refined fluid mechanics mesh near the arterial walls, and a special mapping technique for specifying the velocity profile at inflow boundaries with non-circular shape. In this paper we introduce some additional special techniques, related to the projection of fluid-structure interface stresses, calculation of the wall shear stress (WSS), and calculation of the oscillatory shear index. In the test computations reported here, we focus on WSS calculations in FSI modeling of a patient-specific middle cerebral artery segment with aneurysm. Two different structural mechanics meshes and three different fluid mechanics meshes are tested to investigate the influence of mesh refinement on the WSS calculations. © 2009 Springer-Verlag.

[14]

T.E. Tezduyar, K. Takizawa, C. Moorman, S. Wright, and J. Christopher, “Multiscale sequentially-coupled arterial FSI technique”, Computational Mechanics, 46 (2010) 17–29, 10.1007/s00466-009-0423-2
Times Cited in Web of Science Core Collection: 76, Times Cited in Scopus: 83
@ARTICLE{Tezduyar09e, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and C.~Moorman and S.~Wright and J.~Christopher}, JOURNAL = {Computational Mechanics}, TITLE = {Multiscale Sequentially-Coupled Arterial {FSI} Technique}, VOLUME = {46}, YEAR = {2010}, PAGES = {17–29}, DOI = {10.1007/s00466-009-0423-2} } Abstract:
Multiscale versions of the Sequentially-Coupled Arterial Fluid-Structure Interaction (SCAFSI) technique are presented. The SCAFSI technique was introduced as an approximate FSI approach in arterial fluid mechanics. It is based on the assumption that the arterial deformation during a cardiac cycle is driven mostly by the blood pressure. First we compute a “reference” arterial deformation as a function of time, driven only by the blood pressure profile of the cardiac cycle. Then we compute a sequence of updates involving mesh motion, fluid dynamics calculations, and recomputing the arterial deformation. The SCAFSI technique was developed and tested in conjunction with the stabilized space-time FSI (SSTFSI) technique. Beyond providing a computationally more economical alternative to the fully coupled arterial FSI approach, the SCAFSI technique brings additional flexibility, such as being able to carry out the computations in a spatially or temporally multiscale fashion. In the test computations reported here for the spatially multiscale versions of the SCAFSI technique, we focus on a patient-specific middle cerebral artery segment with aneurysm, where the arterial geometry is based on computed tomography images. The arterial structure is modeled with the continuum element made of hyperelastic (Fung) material. © 2009 Springer-Verlag.

[13]

M. Manguoglu, K. Takizawa, A.H. Sameh, and T.E. Tezduyar, “Solution of linear systems in arterial fluid mechanics computations with boundary layer mesh refinement”, Computational Mechanics, 46 (2010) 83–89, 10.1007/s00466-009-0426-z
Times Cited in Web of Science Core Collection: 45, Times Cited in Scopus: 45
@ARTICLE{Manguoglu09a, AUTHOR = {M.~Manguoglu and K.~Takizawa and A. H.~Sameh and T. E.~Tezduyar}, JOURNAL = {Computational Mechanics}, TITLE = {Solution of Linear Systems in Arterial Fluid Mechanics Computations with Boundary Layer Mesh Refinement}, VOLUME = {46}, YEAR = {2010}, PAGES = {83–89}, DOI = {10.1007/s00466-009-0426-z} } Abstract:
Computation of incompressible flows in arterial fluid mechanics, especially because it involves fluid-structure interaction, poses significant numerical challenges. Iterative solution of the fluid mechanics part of the equation systems involved is one of those challenges, and we address that in this paper, with the added complication of having boundary layer mesh refinement with thin layers of elements near the arterial wall. As test case, we use matrix data from stabilized finite element computation of a bifurcating middle cerebral artery segment with aneurysm. It is well known that solving linear systems that arise in incompressible flow computations consume most of the time required by such simulations. For solving these large sparse nonsymmetric systems, we present effective preconditioning techniques appropriate for different stages of the computation over a cardiac cycle. © 2009 Springer-Verlag.

[12]

K. Takizawa, J. Christopher, T.E. Tezduyar, and S. Sathe, “Space–time finite element computation of arterial fluid–structure interactions with patient-specific data”, International Journal for Numerical Methods in Biomedical Engineering, 26 (2010) 101–116, 10.1002/cnm.1241
Times Cited in Web of Science Core Collection: 102, Times Cited in Scopus: 112
@ARTICLE{Takizawa09a, AUTHOR = {K.~Takizawa and J.~Christopher and T. E.~Tezduyar and S.~Sathe}, JOURNAL = {International Journal for Numerical Methods in Biomedical Engineering}, TITLE = {Space–Time Finite Element Computation of Arterial Fluid–Structure Interactions with Patient-Specific Data}, VOLUME = {26}, YEAR = {2010}, PAGES = {101–116}, DOI = {10.1002/cnm.1241} } Abstract:
The stabilized space-time fluid-structure interaction (SSTFSI) technique developed by the team for advanced flow simulation and modeling is applied to the computation of arterial fluid-structure interaction (FSI) with patient-specific data. The SSTFSI technique is based on the deforming-spatial-domain/stabilized space-time formulation and is supplemented with a number of special techniques developed for arterial FSI. These include a recipe for pre-FSI computations that improve the convergence of the FSI computations, using an estimated zero-pressure arterial geometry, layers of refined fluid mechanics mesh near the arterial walls, and a special mapping technique for specifying the velocity profile at an inflow boundary with non-circular shape. In the test computations reported here, we focus on a patient-specific middle cerebral artery segment with aneurysm, where the arterial geometry is based on computed tomography images. Copyright © 2009 John Wiley & Sons, Ltd.

[11]

Y. Imai, T. Aoki, and K. Takizawa, “Conservative form of interpolated differential operator scheme for compressible and incompressible fluid dynamics”, Journal of Computational Physics, 227 (2008) 2263–2285, 10.1016/j.jcp.2007.11.031
Times Cited in Web of Science Core Collection: 19, Times Cited in Scopus: 25
@ARTICLE{Imai08a, AUTHOR = {Y.~Imai and T.~Aoki and K.~Takizawa}, JOURNAL = {Journal of Computational Physics}, TITLE = {Conservative Form of Interpolated Differential Operator Scheme for Compressible and Incompressible Fluid Dynamics}, VOLUME = {227}, YEAR = {2008}, PAGES = {2263–2285}, DOI = {10.1016/j.jcp.2007.11.031} } Abstract:
The proposed scheme, which is a conservative form of the interpolated differential operator scheme (IDO-CF), can provide high accurate solutions for both compressible and incompressible fluid equations. Spatial discretizations with fourth-order accuracy are derived from interpolation functions locally constructed by both cell-integrated values and point values. These values are coupled and time-integrated by solving fluid equations in the flux forms for the cell-integrated values and in the derivative forms for the point values. The IDO-CF scheme exactly conserves mass, momentum, and energy, retaining the high resolution more than the non-conservative form of the IDO scheme. A direct numerical simulation of turbulence is carried out with comparable accuracy to that of spectral methods. Benchmark tests of Riemann problems and lid-driven cavity flows show that the IDO-CF scheme is immensely promising in compressible and incompressible fluid dynamics studies. © 2007 Elsevier Inc.

[10]

K. Takizawa, K. Tanizawa, T. Yabe, and T.E. Tezduyar, “Ship hydrodynamics computations with the CIP method based on adaptive Soroban grids”, International Journal for Numerical Methods in Fluids, 54 (2007) 1011–1019, 10.1002/fld.1466
Times Cited in Web of Science Core Collection: 23, Times Cited in Scopus: 30
@ARTICLE{Takizawa07a, AUTHOR = {K.~Takizawa and K.~Tanizawa and T.~Yabe and T. E.~Tezduyar}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {Ship Hydrodynamics Computations with the {CIP} Method Based on Adaptive {S}oroban Grids}, VOLUME = {54}, YEAR = {2007}, PAGES = {1011–1019}, DOI = {10.1002/fld.1466} } Abstract:
The constrained interpolation profile/cubic interpolated pseudo-particle (CIP) combined unified procedure (CCUP) method (J. Phys. Soc. Jpn. 1991; 60:2105-2108), which is based on the CIP method (J. Comput. Phys. 1985; 61:261-268; J. Comput. Phys. 1987; 70:355-372; Comput. Phys. Commun. 1991; 66:219-232; J. Comput. Phys. 2001; 169:556-593) and the adaptive Soroban grid technique (J. Comput. Phys. 2004; 194:55-77) were combined in (Comput. Mech. 2006; published online) for computation of 3D fluid-object and fluid-structure interactions in the presence of free surfaces and fluid-fluid interfaces. Although the grid system is unstructured, it still has a very simple data structure and this facilitates computational efficiency. Despite the unstructured and collocated features of the grid, the method maintains high-order accuracy and computational robustness. Furthermore, the meshless feature of the combined technique brings freedom from mesh moving and distortion issues. In this paper, the combined technique is extended to ship hydrodynamics computations. We introduce a new way of computing the advective terms to increase the efficiency in that part of the computations. This is essential in ship hydrodynamics computations where the level of grid refinement needed near the ship surface and at the free surface results in very large grid sizes. The test cases presented are a test computation with a wave-making wedge and simulation of the hydrodynamics of a container ship. Copyright © 2007 John Wiley & Sons, Ltd.

[ 9]

T. Yabe, K. Takizawa, T.E. Tezduyar, and H.-N. Im, “Computation of fluid–solid and fluid–fluid interfaces with the CIP method based on adaptive Soroban grids — An overview”, International Journal for Numerical Methods in Fluids, 54 (2007) 841–853, 10.1002/fld.1473
Times Cited in Web of Science Core Collection: 17, Times Cited in Scopus: 20
@ARTICLE{Yabe07a, AUTHOR = {T.~Yabe and K.~Takizawa and T. E.~Tezduyar and Hyo-Nam Im}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {Computation of Fluid–Solid and Fluid–Fluid Interfaces with the {CIP} Method Based on Adaptive {S}oroban Grids — {A}n Overview}, VOLUME = {54}, YEAR = {2007}, PAGES = {841–853}, DOI = {10.1002/fld.1473} } Abstract:
We provide an overview of how fluid-solid and fluid-fluid interfaces can be computed successfully with the constrained interpolation profile/ cubic interpolated pseudo-particle (CIP) method (J. Comput. Phys. 1985; 61:261-268; Comput. Phys. Commun. 1991; 66:219-232; Comput. Phys. Commun. 1991; 66: 233-242; J. Comput. Phys. 2001; 169:556-593) based on adaptive Soroban grids (J. Comput. Phys. 2004; 194:57-77). In this approach, the CIP combined unified procedure (CCUP) technique (J. Phys. Soc. Jpn 1991; 60:2105-2108), which is based on the CIP method, is combined with the adaptive Soroban grid technique. One of the superior features of the approach is that even though the grid system is unstructured, it still has a simple data structure that renders remarkable computational efficiency. Another superior feature is that despite the unstructured and collocated nature of the grid, high-order accuracy and computational robustness are maintained. In addition, because the Soroban grid technique does not have any elements or cells connecting the grid points, the approach does not involve mesh distortion limitations. While the details of the approach and several numerical examples were reported in (Comput. Mech. 2006; published online), our objective in this paper is to provide an easy-to-follow description of the key aspects of the approach. Copyright © 2007 John Wiley & Sons, Ltd.

[ 8]

K. Takizawa, T. Yabe, Y. Tsugawa, T.E. Tezduyar, and H. Mizoe, “Computation of free–surface flows and fluid–object interactions with the CIP method based on adaptive meshless Soroban grids”, Computational Mechanics, 40 (2007) 167–183, 10.1007/s00466-006-0093-2
Times Cited in Web of Science Core Collection: 65, Times Cited in Scopus: 76
@ARTICLE{Takizawa06a, AUTHOR = {K.~Takizawa and T.~Yabe and Y.~Tsugawa and T. E.~Tezduyar and H.~Mizoe}, JOURNAL = {Computational Mechanics}, TITLE = {Computation of Free–Surface Flows and Fluid–Object Interactions with the {CIP} Method Based on Adaptive Meshless {S}oroban Grids}, VOLUME = {40}, YEAR = {2007}, PAGES = {167–183}, DOI = {10.1007/s00466-006-0093-2} } Abstract:
The CIP Method [J comput phys 61:261-268 1985; J comput phys 70:355-372, 1987; Comput phys commun 66:219-232 1991; J comput phys 169:556-593, 2001] and adaptive Soroban grid [J comput phys 194:57-77, 2004] are combined for computation of three- dimensional fluid-object and fluid-structure interactions, while maintaining high-order accuracy. For the robust computation of free-surface and multi-fluid flows, we adopt the CCUP method [Phys Soc Japan J 60:2105-2108 1991]. In most of the earlier computations, the CCUP method was used with a staggered-grid approach. Here, because of the meshless nature of the Soroban grid, we use the CCUP method with a collocated-grid approach. We propose an algorithm that is stable, robust and accurate even with such collocated grids. By adopting the CIP interpolation, the accuracy is largely enhanced compared to linear interpolation. Although this grid system is unstructured, it still has a very simple data structure. © Springer Verlag 2007.

[ 7]

T. Yabe, K. Takizawa, M. Chino, M. Imai, and C.C. Chu, “Challenge of CIP as a universal solver for solid, liquid and gas”, International Journal for Numerical Methods in Fluids, 47 (2005) 655–676, 10.1002/fld.830
Times Cited in Web of Science Core Collection: 19, Times Cited in Scopus: 24
@ARTICLE{Yabe05a, AUTHOR = {T.~Yabe and K.~Takizawa and M.~Chino and M.~Imai and C. C.~Chu}, JOURNAL = {International Journal for Numerical Methods in Fluids}, TITLE = {Challenge of {CIP} as a universal solver for solid, liquid and gas}, VOLUME = {47}, YEAR = {2005}, PAGES = {655–676}, DOI = {10.1002/fld.830} } Abstract:
We review some recent progress of the CIP method that is known as a general numerical solver for solid, liquid, gas and plasmas. This method is a kind of semi-Lagrangian scheme and has been extended to treat incompressible flow in the framework of compressible fluid. Since it uses primitive Euler representation, it is suitable for multi-phase analysis. Some applications to skimmer, swimming fish and laser cutting are presented. This method is recently extended to almost mesh-free system that is called ‘soroban grid’ that ensures the third-order accuracy both in time and space with the help of the CIP method. Copyright © 2005 John Wiley & Sons, Ltd.

[ 6]

K. Takizawa, T. Yabe, M. Chino, T. Kawai, K. Wataji, H. Hoshino, and T. Watanabe, “Simulation and experiment on swimming fish and skimmer by CIP method”, Computers & Structures, 83 (2005) 397–408, 10.1016/j.compstruc.2004.04.023
Times Cited in Web of Science Core Collection: 8, Times Cited in Scopus: 9
@ARTICLE{Takizawa05a, AUTHOR = {K.~Takizawa and T.~Yabe and M.~Chino and T.~Kawai and K.~Wataji and H.~Hoshino and T.~Watanabe}, JOURNAL = {Computers \& Structures}, TITLE = {Simulation and Experiment on Swimming Fish and Skimmer by {CIP} Method}, VOLUME = {83}, YEAR = {2005}, PAGES = {397–408}, DOI = {10.1016/j.compstruc.2004.04.023} } Abstract:
The Cubic-Interpolated Propagation/Constrained Interpolation Profile (CIP) method is applied to the fluid-structure interaction like swimming fish and skimmer in the Cartesian grid system. These subjects require accurate calculation of pressure on the surface of the moving body. Using the accurate profile of pressure inside a grid cell, we estimate the force acting on the rigid body even if the rigid body has a structure in a scale smaller than grid cell. The CIP method is used to define such subgrid-scale structure. The experiments are performed to show the accuracy of the simulations. © 2005 Published by Elsevier Ltd.

[ 5]

T. Yabe, H. Mizoe, K. Takizawa, H. Moriki, H. Im, and Y. Ogata, “Higher-order schemes with CIP method and adaptive Soroban grid towards mesh-free scheme”, Journal of Computational Physics, 194 (2004) 57–77, 10.1016/j.jcp.2003.08.019
Times Cited in Web of Science Core Collection: 54, Times Cited in Scopus: 66
@ARTICLE{Yabe04c, AUTHOR = {T.~Yabe and H.~Mizoe and K.~Takizawa and H.~Moriki and H.~Im and Y.~Ogata}, JOURNAL = {Journal of Computational Physics}, TITLE = {Higher-Order Schemes with {CIP} Method and Adaptive {S}oroban Grid Towards Mesh-Free Scheme}, VOLUME = {194}, YEAR = {2004}, PAGES = {57–77}, DOI = {10.1016/j.jcp.2003.08.019} } Abstract:
A new class of body-fitted grid system that can keep the third-order accuracy in time and space is proposed with the help of the CIP (constrained interpolation profile/cubic interpolated propagation) method. The grid system consists of the straight lines and grid points moving along these lines like abacus – Soroban in Japanese. The length of each line and the number of grid points in each line can be different. The CIP scheme is suitable to this mesh system and the calculation of large CFL (>10) at locally refined mesh is easily performed. Mesh generation and searching of upstream departure point are very simple and almost mesh-free treatment is possible. Adaptive grid movement and local mesh refinement are demonstrated. © 2003 Elsevier B.V. All rights reserved.

[ 4]

T. Yabe, K. Takizawa, F. Xiao, T. Aoki, T. Himeno, T. Takahashi, and A. Kunimatsu, “A new paradigm of computer graphics by universal solver for solid, liquid and gas”, Japan Society of Mechanical Engineers International Journal. Ser. B, Fluids and Thermal Engineering, 47 (2004) 653–663, 10.1299/jsmeb.47.656
Times Cited in Web of Science Core Collection: 1, Times Cited in Scopus: 1
@ARTICLE{Yabe04b, AUTHOR = {T.~Yabe and K.~Takizawa and F.~Xiao and T.~Aoki and T.~Himeno and T.~Takahashi and A.~Kunimatsu}, JOURNAL = {Japan Society of Mechanical Engineers International Journal. Ser. B, Fluids and Thermal Engineering}, TITLE = {A New Paradigm of Computer Graphics by Universal Solver for Solid, Liquid and Gas}, VOLUME = {47}, YEAR = {2004}, PAGES = {653–663}, DOI = {10.1299/jsmeb.47.656} } Abstract:
We propose a new algorithm for producing computer graphics of melting and evaporation process of matter. Such a computation becomes possible by a universal solver for solid, liquid and gas based on the CIP (Cubic-Interpolated Propagation/Constrained Interpolation Profile) method proposed by one of the authors. This method can also be applied to the movement, deformation and even break up of solid, liquid and gas in one simple algorithm. Therefore seamless computation of all the phases of matter becomes possible. This enables us to reproduce natural phenomena in some instances by computation. In order to demonstrate this reality, we show how precisely the computational result replicates the movies of real phenomena. The flattering motions of metal disk in water and thin name card in air are treated showing accuracy of force calculation on the surface of sub-grid scale. Although the CIP uses semi-Lagrangian form algorithm, the exact mass conservation is guaranteed by additional tool. By using this scheme, separation of a bubble in bifurcation tube and splashing of water surface are successfully simulated.

[ 3]

K. Takizawa, T. Yabe, and T. Nakamura, “Multi-dimensional semi-Lagrangian scheme that guarantees exact conservation”, Computer Physics Communications, 148 (2002) 137–159, 10.1016/S0010-4655(02)00472-1
Times Cited in Web of Science Core Collection: 19, Times Cited in Scopus: 20
@ARTICLE{Takizawa02a, AUTHOR = {K.~Takizawa and T.~Yabe and T.~Nakamura}, JOURNAL = {Computer Physics Communications}, TITLE = {Multi-dimensional Semi-{L}agrangian Scheme that Guarantees Exact Conservation}, VOLUME = {148}, YEAR = {2002}, PAGES = {137–159}, DOI = {10.1016/S0010-4655(02)00472-1} } Abstract:
A new numerical method that guarantees exact mass conservation is proposed to solve multi-dimensional hyperbolic equations in semi-Lagrangian form without directional splitting. The method is based on a concept of CIP scheme and keep the many good characteristics of the original CIP scheme. The CIP strategy is applied to the integral form of variable. Although the advection and non-advection terms are separately treated, the mass conservation is kept in a form of spatial profile inside a grid cell. Therefore, it retains various advantages of the semi-Lagrangian schemes with exact conservation that has been beyond the capability of conventional semi-Lagrangian schemes. © Elsevier Science Ltd. All rights reserved.

[ 2]

T. Yabe, Y. Ogata, K. Takizawa, T. Kawai, A. Segawa, and K. Sakurai, “The next generation CIP as a conservative semi-Lagrangian solver for solid, liquid and gas”, Journal of Computational and Applied Mathematics, 149 (2002) 267–277, 10.1016/S0377-0427(02)00535-6
Times Cited in Web of Science Core Collection: 22, Times Cited in Scopus: 31
@ARTICLE{Yabe02a, AUTHOR = {T.~Yabe and Y.~Ogata and K.~Takizawa and T.~Kawai and A.~Segawa and K.~Sakurai}, JOURNAL = {Journal of Computational and Applied Mathematics}, TITLE = {The Next Generation {CIP} as a Conservative Semi-{L}agrangian Solver for Solid, Liquid and Gas}, VOLUME = {149}, YEAR = {2002}, PAGES = {267–277}, DOI = {10.1016/S0377-0427(02)00535-6} } Abstract:
We present a review of the CIP method, which is a kind of semi-Lagrangian scheme and has been extended to treat incompressible flow in the framework of compressible fluid. Since it uses primitive Euler representation, it is suitable for multi-phase analysis. The recent version of this method guarantees the exact mass conservation even in the framework of semi-Lagrangian scheme. Comprehensive review is given for the strategy of the CIP method that has a compact support and subcell resolution including front capturing algorithm with functional transformation. © 2002 Elsevier Science B.V. All rights reserved.

[ 1]

T. Nakamura, R. Tanaka, T. Yabe, and K. Takizawa, “Exactly conservative semi-Lagrangian scheme for multi-dimensional hyperbolic equations”, Journal of Computational Physics, 174 (2001) 171–207, 10.1006/jcph.2001.6888
Times Cited in Web of Science Core Collection: 107, Times Cited in Scopus: 129
@ARTICLE{Nakamura01a, AUTHOR = {T.~Nakamura and R.~Tanaka and T.~Yabe and K.~Takizawa}, JOURNAL = {Journal of Computational Physics}, TITLE = {Exactly Conservative Semi-{L}agrangian Scheme for Multi-dimensional Hyperbolic Equations}, VOLUME = {174}, YEAR = {2001}, PAGES = {171–207}, DOI = {10.1006/jcph.2001.6888} } Abstract:
A new numerical method that guarantees exact mass conservation is proposed to solve multidimensional hyperbolic equations in semi-Lagrangian form. The method is based on the constrained interpolation profile (CIP) scheme and keeps the many good characteristics of the original CIP scheme. The CIP strategy is applied to the integral form of variables. Although the advection and nonadvection terms are separately treated, mass conservation is kept in the form of a spatial profile inside a grid cell. Therefore, it retains various advantages of the semi-Lagrangian solution with exact conservation, which has been beyond the capability of conventional semi-Lagrangian schemes. © 2001 Elsevier Science.

Other Journal Articles

[ 7]

K. Takizawa, Y. Bazilevs, T.E. Tezduyar, M.-C. Hsu, and T. Terahara, “Computational cardiovascular medicine with isogeometric analysis”, Journal of Advanced Engineering and Computation, 6 (2022) 167–199, 10.55579/jaec.202263.381
@ARTICLE{Takizawa22b, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and Ming-Chen Hsu and T.~Terahara}, JOURNAL = {Journal of Advanced Engineering and Computation}, TITLE = {Computational Cardiovascular Medicine With Isogeometric Analysis}, VOLUME = {6}, YEAR = {2022}, PAGES = {167–199}, DOI = {10.55579/jaec.202263.381} }

[ 6]

K. Takizawa, Y. Bazilevs, and T.E. Tezduyar, “Mesh moving methods in flow computations with the space–time and arbitrary Lagrangian–Eulerian methods”, Journal of Advanced Engineering and Computation, 6 (2022) 85–112, 10.55579/jaec.202262.377
@ARTICLE{Takizawa22a, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar}, JOURNAL = {Journal of Advanced Engineering and Computation}, TITLE = {Mesh Moving Methods in Flow Computations With the Space–Time and Arbitrary {L}agrangian–{E}ulerian Methods}, VOLUME = {6}, YEAR = {2022}, PAGES = {85–112}, DOI = {10.55579/jaec.202262.377} }

[ 5]

K. Takizawa, Y. Bazilevs, T.E. Tezduyar, and A. Korobenko, “Computational flow analysis in aerospace, energy and transportation technologies with the variational multiscale methods”, Journal of Advanced Engineering and Computation, 4 (2020) 83–117, 10.25073/jaec.202042.279
@ARTICLE{Takizawa20a, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and A.~Korobenko}, JOURNAL = {Journal of Advanced Engineering and Computation}, TITLE = {Computational Flow Analysis in Aerospace, Energy and Transportation Technologies with the Variational Multiscale Methods}, VOLUME = {4}, YEAR = {2020}, PAGES = {83–117}, DOI = {10.25073/jaec.202042.279} }

[ 4]

Y. Bazilevs, K. Takizawa, T.E. Tezduyar, M.-C. Hsu, Y. Otoguro, H. Mochizuki, and M.C.H. Wu, “Wind turbine and turbomachinery computational analysis with the ALE and space–time variational multiscale methods and isogeometric discretization”, Journal of Advanced Engineering and Computation, 4 (2020) 1–32, 10.25073/jaec.202041.278
@ARTICLE{Bazilevs20a, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar and Ming-Chen Hsu and Y.~Otoguro and H.~Mochizuki and M. C. H.~Wu}, JOURNAL = {Journal of Advanced Engineering and Computation}, TITLE = {Wind Turbine and Turbomachinery Computational Analysis with the {ALE} and Space–Time Variational Multiscale Methods and Isogeometric Discretization}, VOLUME = {4}, YEAR = {2020}, PAGES = {1–32}, DOI = {10.25073/jaec.202041.278} }

[ 3]

K. Takizawa, Y. Bazilevs, T.E. Tezduyar, and M.-C. Hsu, “Computational cardiovascular flow analysis with the variational multiscale methods”, Journal of Advanced Engineering and Computation, 3 (2019) 366–405, 10.25073/jaec.201932.245
@ARTICLE{Takizawa19a, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and Ming-Chen Hsu}, JOURNAL = {Journal of Advanced Engineering and Computation}, TITLE = {Computational Cardiovascular Flow Analysis with the Variational Multiscale Methods}, VOLUME = {3}, YEAR = {2019}, PAGES = {366–405}, DOI = {10.25073/jaec.201932.245} }

[ 2]

K. Takizawa, T.E. Tezduyar, and T. Kanai, “Spacecraft-parachute computational analysis and compressible-flow extensions”, Japan Aeronautical and Space Sciences Magazine, 65 (2017) 280–283 in Japanese, 10.14822/kjsass.65.9_280
@ARTICLE{Takizawa17d, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Kanai}, JOURNAL = {Japan Aeronautical and Space Sciences Magazine}, TITLE = {Spacecraft-Parachute Computational Analysis and Compressible-Flow Extensions}, VOLUME = {65}, NUMBER = {9}, YEAR = {2017}, PAGES = {280–283}, DOI = {10.14822/kjsass.65.9_280}, NOTE = {in Japanese} }

[ 1]

K. Takizawa and T.E. Tezduyar, “Main aspects of the space–time computational FSI techniques and examples of challenging problems solved”, Mechanical Engineering Reviews, 1 (2014) CM0005 inaugural issue, 10.1299/mer.2014cm0005
@ARTICLE{Takizawa13f, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, JOURNAL = {Mechanical Engineering Reviews}, TITLE = {Main Aspects of the Space–Time Computational {FSI} Techniques and Examples of Challenging Problems Solved}, VOLUME = {1}, YEAR = {2014}, PUBLISHER = {Japan Society of Mechanical Engineers}, PAGES = {CM0005}, DOI = {10.1299/mer.2014cm0005}, NOTE = {{\bf inaugural issue}} }

Chapters in Books

[27]

K. Takizawa, T. Terahara, and T.E. Tezduyar, “Space–time flow computation with contact between the moving solid surfaces”, Current Trends and Open Problems in Computational Mechanics (2022) 517–525, 10.1007/978-3-030-87312-7_50
Times Cited in Scopus: 13
@INCOLLECTION{Takizawa20c, AUTHOR = {K.~Takizawa and T.~Terahara and T. E.~Tezduyar}, TITLE = {Space–Time Flow Computation with Contact Between the Moving Solid Surfaces}, VOLUME = {None}, YEAR = {2022}, PUBLISHER = {Springer}, BOOKTITLE = {Current Trends and Open Problems in Computational Mechanics}, EDITOR = {F.~Aldakheel and B.~Hudobivnik and M.~Soleimani and H.~Wessels and C.~Weissenfels and M.~Marino}, PAGES = {517–525}, DOI = {10.1007/978-3-030-87312-7_50}, ISBN = {978-3-030-87312-7} } Abstract:
In computation of flow problems with moving boundaries and interfaces, including fluid-structure interaction, moving the fluid mechanics mesh to follow the fluid-solid interface enables mesh-resolution control near the interface. Therefore moving-mesh methods, such as the Space-Time Variational Multiscale (ST-VMS) method, enable high-resolution boundary-layer representation near fluid-solid interfaces and thus higher accuracy in such critical flow regions. In flow problems with contact between solid surfaces, until recently, one had to either give up on representing the actual contact and leave a small gap or give up on using a moving-mesh method and thus give up on having high-fidelity flow solution near the solid surfaces. The ST Topology Change (ST-TC) method changed all that. Now we can both represent the actual contact and have high-fidelity flow solution near the solid surfaces. With the ST-VMS, which serves as the core method, and the ST-TC and two other special methods, the ST Slip Interface method and ST Isogeometric Analysis, we have created a powerful computational framework. The new framework is enabling high-fidelity computational flow analysis of some of the most complex problems, such as the ventricle-valve-aorta sequence. This chapter is a description and demonstration of that framework.

[26]

T.E. Tezduyar, K. Takizawa, and T. Kuraishi, “Space–time computational FSI and flow analysis: 2004 and beyond”, Current Trends and Open Problems in Computational Mechanics (2022) 537–544, 10.1007/978-3-030-87312-7_52
Times Cited in Scopus: 15
@INCOLLECTION{Tezduyar20a, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and T.~Kuraishi}, TITLE = {Space–Time Computational {FSI} and Flow Analysis: 2004 and Beyond}, VOLUME = {None}, YEAR = {2022}, PUBLISHER = {Springer}, BOOKTITLE = {Current Trends and Open Problems in Computational Mechanics}, EDITOR = {F.~Aldakheel and B.~Hudobivnik and M.~Soleimani and H.~Wessels and C.~Weissenfels and M.~Marino}, PAGES = {537–544}, DOI = {10.1007/978-3-030-87312-7_52}, ISBN = {978-3-030-87312-7} } Abstract:
The space-time (ST) computational fluid-structure interaction (FSI) and flow analysis started in 1990, with the inception of the Deforming-Spatial- Domain/Stabilized ST (DSD/SST) method. In 1990-2003, the DSD/SST enabled computational FSI and flowanalysis in many complex engineering problems, including parachute FSI and fluid-particle interaction with 1000 spheres. In 2004, the DSD/SST enabled some of the earliest cardiovascular FSI analyses, and, in combination with the “quasi-direct coupling, ” enabled more robust FSI analysis for very light structures, such as large parachutes. New core and special ST methods introduced in 2006 and 2007 enabled computational FSI analysis of the Orion spacecraft parachutes, with hundreds and gaps and slits that the flow goes through. In 2004, the first author also met the second author, which eventually led to a unique research collaboration and a new generation of ST methods. It also led to some of the most complex computational FSI and flow analyses, ranging from clusters of spacecraft parachutes with contact between the parachutes to heart valves to flow around tires with road contact and tire deformation. This chapter is the story of the ST computational FSI and flow analysis in 2004 and beyond.

[25]

K. Takizawa, Y. Bazilevs, T.E. Tezduyar, and A. Korobenko, “Variational multiscale flow analysis in aerospace, energy and transportation technologies”, Parallel Algorithms in Computational Science and Engineering (2020) 235–280, 10.1007/978-3-030-43736-7_8
Times Cited in Scopus: 20
@INCOLLECTION{Takizawa19c, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and A.~Korobenko}, TITLE = {Variational Multiscale Flow Analysis in Aerospace, Energy and Transportation Technologies}, VOLUME = {None}, YEAR = {2020}, PUBLISHER = {Springer}, BOOKTITLE = {Parallel Algorithms in Computational Science and Engineering}, EDITOR = {A.~Grama and A.~Sameh}, PAGES = {235–280}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-030-43736-7_8}, ISBN = {978-3-030-43735-0} } Abstract:
Computational flow analysis is now playing a key role in aerospace, energy and transportation technologies, bringing solution in challenging problems such as aerodynamics of parachutes, thermo-fluid analysis of ground vehicles and tires, and fluid–structure interaction (FSI) analysis of wind turbines. The computational challenges include complex geometries, moving boundaries and interfaces, FSI, turbulent flows, rotational flows, and large problem sizes. The Residual-Based Variational Multiscale (RBVMS), ALE-VMS and Space–Time VMS (ST-VMS) methods have been quite successful serving as core methods in addressing the computational challenges. The core methods are supplemented with special methods targeting specific classes of problems, such as the Slip Interface (SI) method, Multi-Domain Method, and the “ST-C” data compression method. We describe the core and special methods. We present, as examples of challenging computations performed with these methods, aerodynamic analysis of a ram-air parachute, thermo-fluid analysis of a freight truck and its rear set of tires, and aerodynamic and FSI analysis of two back-to-back wind turbines in atmospheric boundary layer flow.

[24]

T.J.R. Hughes, K. Takizawa, Y. Bazilevs, T.E. Tezduyar, and M.-C. Hsu, “Computational cardiovascular analysis with the variational multiscale methods and isogeometric discretization”, Parallel Algorithms in Computational Science and Engineering (2020) 151–193, 10.1007/978-3-030-43736-7_6
Times Cited in Scopus: 24
@INCOLLECTION{Hughes19a, AUTHOR = {T. J. R.~Hughes and K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and Ming-Chen Hsu}, TITLE = {Computational Cardiovascular Analysis with the Variational Multiscale Methods and Isogeometric Discretization}, VOLUME = {None}, YEAR = {2020}, PUBLISHER = {Springer}, BOOKTITLE = {Parallel Algorithms in Computational Science and Engineering}, EDITOR = {A.~Grama and A.~Sameh}, PAGES = {151–193}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-030-43736-7_6}, ISBN = {978-3-030-43735-0} } Abstract:
Computational cardiovascular analysis can provide valuable information to cardiologists and cardiovascular surgeons on a patient-specific basis. There are many computational challenges that need to be faced in this class of flow analyses. They include highly unsteady flows, complex cardiovascular geometries, moving boundaries and interfaces, such as the motion of the heart valve leaflets, contact between moving solid surfaces, such as the contact between the leaflets, and the fluid–structure interaction between blood and cardiovascular structure. Many of these challenges have been or are being addressed by the Space–Time Variational Multiscale (ST-VMS) method, the Arbitrary Lagrangian–Eulerian VMS (ALE-VMS) method, and VMS-based immersogeometric analysis (IMGA-VMS), which serve as the core computational methods, and other special methods used in combination with them. We provide an overview of these methods and present examples of challenging computations carried out with them, including aortic and heart valve flow analyses. We also point out that these methods are general computational fluid dynamics techniques and have broad applicability to a wide range of other areas of science and engineering.

[23]

Y. Bazilevs, K. Takizawa, T.E. Tezduyar, M.-C. Hsu, Y. Otoguro, H. Mochizuki, and M.C.H. Wu, “ALE and space–time variational multiscale isogeometric analysis of wind turbines and turbomachinery”, Parallel Algorithms in Computational Science and Engineering (2020) 195–233, 10.1007/978-3-030-43736-7_7
Times Cited in Scopus: 26
@INCOLLECTION{Bazilevs19b, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar and Ming-Chen Hsu and Y.~Otoguro and H.~Mochizuki and M. C. H.~Wu}, TITLE = {{ALE} and Space–Time Variational Multiscale Isogeometric Analysis of Wind Turbines and Turbomachinery}, VOLUME = {None}, YEAR = {2020}, PUBLISHER = {Springer}, BOOKTITLE = {Parallel Algorithms in Computational Science and Engineering}, EDITOR = {A.~Grama and A.~Sameh}, PAGES = {195–233}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-030-43736-7_7}, ISBN = {978-3-030-43735-0} } Abstract:
Many of the challenges encountered in computational analysis of wind turbines and turbomachinery are being addressed by the Arbitrary Lagrangian–Eulerian (ALE) and Space–Time (ST) Variational Multiscale (VMS) methods and isogeometric discretization. The computational challenges include turbulent rotational flows, complex geometries, moving boundaries and interfaces, such as the rotor motion, and the fluid–structure interaction (FSI), such as the FSI between the wind turbine blade and the air. The core computational methods are the ALE-VMS and ST-VMS methods. These are supplemented with special methods like the Slip Interface (SI) method and ST Isogeometric Analysis with NURBS basis functions in time. We describe the core and special methods and present, as examples of challenging computations performed, computational analysis of horizontal- and vertical-axis wind turbines and flow-driven string dynamics in pumps.

[22]

A. Korobenko, Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Recent advances in ALE-VMS and ST-VMS computational aerodynamic and FSI analysis of wind turbines”, Frontiers in Computational Fluid–Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty – 2018 (2018) 253–336, 10.1007/978-3-319-96469-0_7
Times Cited in Scopus: 49
@INCOLLECTION{Korobenko18a, AUTHOR = {A.~Korobenko and Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Recent Advances in {ALE-VMS} and {ST-VMS} Computational Aerodynamic and {FSI} Analysis of Wind Turbines}, VOLUME = {None}, YEAR = {2018}, PUBLISHER = {Springer}, BOOKTITLE = {Frontiers in Computational Fluid–Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty — 2018}, EDITOR = {T. E.~Tezduyar}, PAGES = {253–336}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-319-96469-0_7}, ISBN = {978-3-319-96468-3} } Abstract:
We describe the recent advances made by our teams in ALE-VMS and ST-VMS computational aerodynamic and fluid–structure interaction (FSI) analysis of wind turbines. The ALE-VMS method is the variational multiscale version of the Arbitrary Lagrangian–Eulerian method. The VMS components are from the residual-based VMS method. The ST-VMS method is the VMS version of the Deforming-Spatial-Domain/Stabilized Space–Time method. The ALE-VMS and ST-VMS serve as the core methods in the computations. They are complemented by special methods that include the ALE-VMS versions for stratified flows, sliding interfaces and weak enforcement of Dirichlet boundary conditions, ST Slip Interface (ST-SI) method, NURBS-based isogeometric analysis, ST/NURBS Mesh Update Method (STNMUM), Kirchhoff–Love shell modeling of wind-turbine structures, and full FSI coupling. The VMS feature of the ALE-VMS and ST-VMS addresses the computational challenges associated with the multiscale nature of the unsteady flow, and the moving-mesh feature of the ALE and ST frameworks enables high-resolution computation near the rotor surface. The ST framework, in a general context, provides higher-order accuracy. The ALE-VMS version for sliding interfaces and the ST-SI enable moving-mesh computation of the spinning rotor. The mesh covering the rotor spins with it, and the sliding interface or the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. The ST-SI also enables prescribing the fluid velocity at the turbine rotor surface as weakly-enforced Dirichlet boundary condition. The STNMUM enables exact representation of the mesh rotation. The analysis cases reported include both the horizontal-axis and vertical-axis wind turbines, stratified and unstratified flows, standalone wind turbines, wind turbines with tower or support columns, aerodynamic interaction between two wind turbines, and the FSI between the aerodynamics and structural dynamics of wind turbines. Comparisons with experimental data are also included where applicable. The reported cases demonstrate the effectiveness of the ALE-VMS and ST-VMS computational analysis in wind-turbine aerodynamics and FSI.

[21]

K. Takizawa, T.E. Tezduyar, H. Uchikawa, T. Terahara, T. Sasaki, K. Shiozaki, A. Yoshida, K. Komiya, and G. Inoue, “Aorta flow analysis and heart valve flow and structure analysis”, Frontiers in Computational Fluid–Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty – 2018 (2018) 29–89, 10.1007/978-3-319-96469-0_2
Times Cited in Scopus: 46
@INCOLLECTION{Takizawa18a, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and H.~Uchikawa and T.~Terahara and T.~Sasaki and K.~Shiozaki and A.~Yoshida and K.~Komiya and G.~Inoue}, TITLE = {Aorta Flow Analysis and Heart Valve Flow and Structure Analysis}, VOLUME = {None}, YEAR = {2018}, PUBLISHER = {Springer}, BOOKTITLE = {Frontiers in Computational Fluid–Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty — 2018}, EDITOR = {T. E.~Tezduyar}, PAGES = {29–89}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-319-96469-0_2}, ISBN = {978-3-319-96468-3} } Abstract:
We present our computational methods for and results from aorta flow analysis and heart valve flow and structure analysis. In flow analysis, the core method is the space–time Variational Multiscale (ST-VMS) method. The other key methods are the ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods and the ST Isogeometric Analysis (ST-IGA). The ST framework, in a general context, provides higher-order accuracy. The VMS feature of the ST-VMS addresses the computational challenges associated with the multiscale nature of the unsteady flows in the aorta and heart valve. The moving-mesh feature of the ST framework enables high-resolution computation near the valve leaflets. The ST-SI connects the sectors of meshes containing the leaflets, enabling a more effective mesh moving. The ST-TC enables moving-mesh computation even with the TC created by the contact between the leaflets. It deals with the contact while maintaining high-resolution representation near the leaflets. Integration of the ST-SI and ST-TC enables high-resolution representation even though parts of the SI are coinciding with the leaflet surfaces. It also enables dealing with leaflet–leaflet contact location change and contact sliding. The ST-IGA provides smoother representation of aorta and valve surfaces and increased accuracy in the flow solution. With the integration of the ST-IGA with the ST-SI and ST-TC, the element density in the narrow spaces near the contact areas is kept at a reasonable level. In structure analysis, we use a Kirchhoff–Love shell model, where we take the stretch in the third direction into account in calculating the curvature term. The computations presented demonstrate the scope and effectiveness of the methods.

[20]

T. Kuraishi, K. Takizawa, and T.E. Tezduyar, “Space–time computational analysis of tire aerodynamics with actual geometry, road contact and tire deformation”, Frontiers in Computational Fluid–Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty – 2018 (2018) 337–376, 10.1007/978-3-319-96469-0_8
Times Cited in Scopus: 42
@INCOLLECTION{Kuraishi17a, AUTHOR = {T.~Kuraishi and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Space–Time Computational Analysis of Tire Aerodynamics with Actual Geometry, Road Contact and Tire Deformation}, VOLUME = {None}, YEAR = {2018}, PUBLISHER = {Springer}, BOOKTITLE = {Frontiers in Computational Fluid–Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty — 2018}, EDITOR = {T. E.~Tezduyar}, PAGES = {337–376}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-319-96469-0_8}, ISBN = {978-3-319-96468-3} } Abstract:
A new space–time (ST) computational method, “ST-SI-TC-IGA,” is enabling us to address the challenges faced in computational analysis of tire aerodynamics with actual geometry, road contact and tire deformation. The core component of the ST-SI-TC-IGA is the ST Variational Multiscale (ST-VMS) method, and the other key components are the ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods and the ST Isogeometric Analysis (ST-IGA). The VMS feature of the ST-VMS addresses the challenge created by the turbulent nature of the flow, the moving-mesh feature of the ST framework enables high-resolution computation near the moving fluid–solid interfaces, and the higher-order accuracy of the ST framework strengthens both features. The ST-SI enables high-resolution representation of the boundary layers near the tire. The mesh covering the tire spins with it, and the SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the solution. The ST-TC enables moving-mesh computation even with the TC created by the contact between the tire and the road. It deals with the contact while maintaining high-resolution representation near the tire. Integration of the ST-SI and ST-TC enables high-resolution representation even though parts of the SI are coinciding with the tire and road surfaces. It also enables dealing with the tire-road contact location change and contact sliding. By integrating the ST-IGA with the ST-SI and ST-TC, in addition to having a more accurate representation of the tire surfaces and increased accuracy in the flow solution, the element density in the tire grooves and in the narrow spaces near the contact areas is kept at a reasonable level. We present computations with the ST-SI-TC-IGA and two models of flow around a rotating tire with road contact and prescribed deformation. One is a simple 2D model, and one is a 3D model with an actual tire geometry that includes the longitudinal and transverse grooves. The computations show the effectiveness of the ST-SI-TC-IGA in tire aerodynamics.

[19]

Y. Otoguro, K. Takizawa, and T.E. Tezduyar, “A general-purpose NURBS mesh generation method for complex geometries”, Frontiers in Computational Fluid–Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty – 2018 (2018) 399–434, 10.1007/978-3-319-96469-0_10
Times Cited in Scopus: 52
@INCOLLECTION{Otoguro17a, AUTHOR = {Y.~Otoguro and K.~Takizawa and T. E.~Tezduyar}, TITLE = {A General-Purpose {NURBS} Mesh Generation Method for Complex Geometries}, VOLUME = {None}, YEAR = {2018}, PUBLISHER = {Springer}, BOOKTITLE = {Frontiers in Computational Fluid–Structure Interaction and Flow Simulation: Research from Lead Investigators under Forty — 2018}, EDITOR = {T. E.~Tezduyar}, PAGES = {399–434}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-319-96469-0_10}, ISBN = {978-3-319-96468-3} } Abstract:
Spatial discretization with NURBS meshes is increasingly being used in computational analysis, including computational flow analysis with complex geometries. In flow analysis, compared to standard discretization methods, isogeometric discretization provides more accurate representation of the solid surfaces and increased accuracy in the flow solution. The Space-Time Computational Analysis (STCA), where the core method is the ST Variational Multiscale method, is increasingly relying on the ST Isogeometric Analysis (ST-IGA) as one of its key components, quite often also with IGA basis functions in time. The ST Slip Interface (ST-SI) and ST Topology Change methods are two other key components of the STCA, and complementary nature of all these ST methods makes the STCA powerful and practical. To make the ST-IGA use, and in a wider context the IGA use, even more practical in computational flow analysis with complex geometries, NURBS volume mesh generation needs to be easier and more automated. To that end, we present a general-purpose NURBS mesh generation method. The method is based on multi-block-structured mesh generation with existing techniques, projection of that mesh to a NURBS mesh made of patches that correspond to the blocks, and recovery of the original model surfaces to the extent they are suitable for accurate and robust fluid mechanics computations. It is expected to retain the refinement distribution and element quality of the multi-block-structured mesh that we start with. The flexibility of discretization with the general-purpose mesh generation is supplemented with the ST-SI method, which allows, without loss of accuracy, C−1 continuity between NURBS patches and thus removes the matching requirement between the patches. We present mesh-quality performance studies for 2D and 3D meshes, including those for complex models, and test computation for a turbocharger turbine and exhaust manifold. These demonstrate that the general-purpose mesh generation method proposed makes the IGA use in computational flow analysis even more practical.

[18]

K. Takizawa and T.E. Tezduyar, “Space–time computational analysis in energy applications”, Flow Simulation with the Finite Element Method (2017) 278–288
@INCOLLECTION{Takizawa17c, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {Space–time computational analysis in energy applications}, VOLUME = {None}, YEAR = {2017}, PUBLISHER = {Maruzen}, BOOKTITLE = {Flow Simulation with the Finite Element Method}, EDITOR = {None}, PAGES = {278–288}, SERIES = {None}, DOI = {None}, ISBN = {978-4-621-30183-8}, NOTE = {in Japanese} }

[17]

K. Takizawa and T.E. Tezduyar, “Space–time computational methods and applications”, Flow Simulation with the Finite Element Method (2017) 249–269
@INCOLLECTION{Takizawa17b, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {Space–time computational methods and applications}, VOLUME = {None}, YEAR = {2017}, PUBLISHER = {Maruzen}, BOOKTITLE = {Flow Simulation with the Finite Element Method}, EDITOR = {None}, PAGES = {249–269}, SERIES = {None}, DOI = {None}, ISBN = {978-4-621-30183-8}, NOTE = {in Japanese} }

[16]

T. Sawada, H. Watanabe, K. Takizawa, and T.E. Tezduyar, “Fluid–structure interaction analysis”, Flow Simulation with the Finite Element Method (2017) 209–247
@INCOLLECTION{Takizawa17c2, AUTHOR = {T.~Sawada and H.~Watanabe and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Fluid–Structure Interaction Analysis}, VOLUME = {None}, YEAR = {2017}, PUBLISHER = {Maruzen}, BOOKTITLE = {Flow Simulation with the Finite Element Method}, EDITOR = {None}, PAGES = {209–247}, SERIES = {None}, DOI = {None}, ISBN = {978-4-621-30183-8}, NOTE = {in Japanese} }

[15]

K. Takizawa, T.E. Tezduyar, T. Terahara, and T. Sasaki, “Heart valve flow computation with the Space–Time Slip Interface Topology Change (ST-SI-TC) method and Isogeometric Analysis (IGA)”, Biomedical Technology: Modeling, Experiments and Simulation (2018) 77–99, 10.1007/978-3-319-59548-1_6
Times Cited in Web of Science Core Collection: 37, Times Cited in Scopus: 50
@INCOLLECTION{Takizawa16g, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Terahara and T.~Sasaki}, TITLE = {Heart valve flow computation with the {S}pace–{T}ime {S}lip {I}nterface {T}opology {C}hange ({ST-SI-TC}) method and {I}sogeometric {A}nalysis ({IGA})}, VOLUME = {None}, YEAR = {2018}, PUBLISHER = {Springer}, BOOKTITLE = {Biomedical Technology: Modeling, Experiments and Simulation}, EDITOR = {P.~Wriggers and T.~Lenarz}, PAGES = {77–99}, SERIES = {Lecture Notes in Applied and Computational Mechanics}, DOI = {10.1007/978-3-319-59548-1_6}, ISBN = {978-3-319-59547-4} } Abstract:
We present a heart valve flow computation with the Space-Time Slip Interface Topology Change (ST-SI-TC) method and Isogeometric Analysis (IGA). The computation is for a realistic heart valve model with actual contact between the valve leaflets. The ST-SI-TC method integrates the ST-SI and ST-TC methods in the framework of the ST Variational Multiscale (ST-VMS) method. The STVMS method functions as a moving-mesh method, which maintains high-resolution boundary layer representation near the solid surfaces. The ST-TC method was introduced for moving-mesh computation of flow problems with TC, such as contact between the leaflets of a heart valve. It deals with the contact while maintaining highresolution representation near the leaflet surfaces. The ST-SI method was originally introduced to addresses the challenge involved in high-resolution representation of the boundary layers near spinning solid surfaces. The mesh covering a spinning solid surface spins with it, and the SI between that mesh and the rest of the mesh accurately connects the two sides. This maintains the high-resolution representation near solid surfaces. In the context of heart valves, the SI connects the sectors of meshes containing the leaflets, enabling a more effective mesh moving. In that context, the ST-SI-TC method enables high-resolution representation even when the contact is between leaflets that are covered by meshes with SI. It also enables dealing with contact location change or contact and sliding on the SI. With IGA, in addition to having a more accurate representation of the surfaces and increased accuracy in the flow solution, the element density in the narrow spaces near the contact areas is kept at a reasonable level. Furthermore, because the flow representation in the contact area has a wider support in IGA, the flow computation method becomes more robust. The computation we present for an aortic-valve model shows the effectiveness of the ST-SI-TC-IGA method.

[14]

K. Takizawa, T.E. Tezduyar, and T. Sasaki, “Estimation of element-based zero-stress state in arterial FSI computations with isogeometric wall discretization”, Biomedical Technology: Modeling, Experiments and Simulation (2018) 101–122, 10.1007/978-3-319-59548-1_7
Times Cited in Web of Science Core Collection: 29, Times Cited in Scopus: 31
@INCOLLECTION{Takizawa16f, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and T.~Sasaki}, TITLE = {Estimation of element-based zero-stress state in arterial {FSI} computations with isogeometric wall discretization}, VOLUME = {None}, YEAR = {2018}, PUBLISHER = {Springer}, BOOKTITLE = {Biomedical Technology: Modeling, Experiments and Simulation}, EDITOR = {P.~Wriggers and T.~Lenarz}, PAGES = {101–122}, SERIES = {Lecture Notes in Applied and Computational Mechanics}, DOI = {10.1007/978-3-319-59548-1_7}, ISBN = {978-3-319-59547-4} } Abstract:
In patient-specific arterial fluid-structure interaction computations the image-based arterial geometry does not come from a zero-stress state (ZSS), requiring an estimation of the ZSS. A method for estimation of element-based ZSS (EBZSS) was introduced earlier in the context of finite element wall discretization. The method has three main components. 1. An iterative method, which starts with a calculated initial guess, is used for computing the EBZSS such that when a given pressure load is applied, the image-based target shape is matched. 2. A method for straight-tube segments is used for computing the EBZSS so that we match the given diameter and longitudinal stretch in the target configuration and the “opening angle.” 3. An element-based mapping between the artery and straight-tube is extracted from the mapping between the artery and straight-tube segments. This provides the mapping from the arterial configuration to the straight-tube configuration, and from the estimated EBZSS of the straight-tube configuration back to the arterial configuration, to be used as the initial guess for the iterative method that matches the image-based target shape. Here we introduce the version of the EBZSS estimation method with isogeometric wall discretization. With NURBS basis functions, we may be able to use larger elements, consequently less number of elements, compared to linear basis functions. Higher-order NURBS basis functions allow representation of more complex shapes within an element. To show how the new EBZSS estimation method performs, we present 2D test computations with straight-tube configurations.

[13]

A. Castorrini, A. Corsini, F. Rispoli, P. Venturini, K. Takizawa, and T.E. Tezduyar, “SUPG/PSPG computational analysis of rain erosion in wind-turbine blades”, Advances in Computational Fluid–Structure Interaction and Flow Simulation: New Methods and Challenging Computations (2016) 77–96, 10.1007/978-3-319-40827-9_7
Times Cited in Web of Science Core Collection: 16, Times Cited in Scopus: 18
@INCOLLECTION{Castorrini16a, AUTHOR = {A.~Castorrini and A.~Corsini and F.~Rispoli and P.~Venturini and K.~Takizawa and T. E.~Tezduyar}, TITLE = {{SUPG/PSPG} computational analysis of rain erosion in wind-turbine blades}, VOLUME = {None}, YEAR = {2016}, PUBLISHER = {Springer}, BOOKTITLE = {Advances in Computational Fluid–Structure Interaction and Flow Simulation: New Methods and Challenging Computations}, EDITOR = {Y.~Bazilevs and K.~Takizawa}, PAGES = {77–96}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-319-40827-9_7}, ISBN = {978-3-319-40825-5} } Abstract:
Wind-turbine blades exposed to rain can be damaged by erosion if not protected. Although this damage does not typically influence the structural response of the blades,it could heavily degrade the aerodynamic performance,and therefore the power production. We present a method for computational analysis of rain erosion in wind-turbine blades. The method is based on a stabilized finite element fluid mechanics formulation and a finite element particle-cloud tracking method. Accurate representation of the flow would be essential in reliable computational turbomachinery analysis and design. The turbulent-flow nature of the problem is dealt with a RANS model and SUPG/PSPG stabilization,the particle-cloud trajectories are calculated based on the flow field and closure models for the turbulence-particle interaction,and one-way dependence is assumed between the flow field and particle dynamics. The erosion patterns are then computed based on the particle-cloud data.

[12]

H. Suito, K. Takizawa, V.Q.H. Huynh, D. Sze, T. Ueda, and T.E. Tezduyar, “A geometrical-characteristics study in patient-specific FSI analysis of blood flow in the thoracic aorta”, Advances in Computational Fluid–Structure Interaction and Flow Simulation: New Methods and Challenging Computations (2016) 379–386, 10.1007/978-3-319-40827-9_29
Times Cited in Web of Science Core Collection: 33, Times Cited in Scopus: 40
@INCOLLECTION{Suito15a, AUTHOR = {H.~Suito and K.~Takizawa and V. Q. H.~Huynh and D.~Sze and T.~Ueda and T. E.~Tezduyar}, TITLE = {A geometrical-characteristics study in patient-specific {FSI} analysis of blood flow in the thoracic aorta}, VOLUME = {None}, YEAR = {2016}, PUBLISHER = {Springer}, BOOKTITLE = {Advances in Computational Fluid–Structure Interaction and Flow Simulation: New Methods and Challenging Computations}, EDITOR = {Y.~Bazilevs and K.~Takizawa}, PAGES = {379–386}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-319-40827-9_29}, ISBN = {978-3-319-40825-5} } Abstract:
This chapter is on fluid-structure interaction (FSI) analysis of blood flow in the thoracic aorta. The FSI is handled with the Sequentially Coupled Arterial FSI technique. We focus on the relationship between the aorta centerline geometry and the wall shear stress (WSS) distribution. The model centerlines are extracted from the CT scans,and we assume a constant diameter for the artery segment. Then,torsion-free model geometries are generated by projecting the original centerline to its averaged plane of curvature. The WSS distributions for the original and projected geometries are compared to examine the influence of the torsion.

[11]

K. Takizawa and T.E. Tezduyar, “New directions in space–time computational methods”, Advances in Computational Fluid–Structure Interaction and Flow Simulation: New Methods and Challenging Computations (2016) 159–178, 10.1007/978-3-319-40827-9_13
Times Cited in Web of Science Core Collection: 39, Times Cited in Scopus: 42
@INCOLLECTION{Takizawa15c, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {New directions in space–time computational methods}, VOLUME = {None}, YEAR = {2016}, PUBLISHER = {Springer}, BOOKTITLE = {Advances in Computational Fluid–Structure Interaction and Flow Simulation: New Methods and Challenging Computations}, EDITOR = {Y.~Bazilevs and K.~Takizawa}, PAGES = {159–178}, SERIES = {Modeling and Simulation in Science, Engineering and Technology}, DOI = {10.1007/978-3-319-40827-9_13}, ISBN = {978-3-319-40825-5} } Abstract:
This is an overview of some of the new directions we have taken the space-time (ST) computational methods since 2010 in bringing solution and analysis to different classes of challenging engineering problems. The new directions include the variational multiscale (VMS) version of the Deforming-Spatial-Domain/Stabilized ST method,using NURBS basis functions in temporal representation of the unknown variables and motion of the solid surfaces and fluid mechanics meshes,ST techniques with continuous representation in time,ST interface-tracking with topology change,and the ST-VMS method for flow computations with slip interfaces. We describe these new directions and present a few examples.

[10]

T.E. Tezduyar, K. Takizawa, and Y. Bazilevs, “Fluid–structure interaction and flows with moving boundaries and interfaces”, Encyclopedia of Computational Mechanics Second Edition (2017), 10.1002/9781119176817.ecm2069
@INCOLLECTION{Tezduyar15a, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and Y.~Bazilevs}, TITLE = {Fluid–Structure Interaction and Flows with Moving Boundaries and Interfaces}, YEAR = {December 2017}, PUBLISHER = {Wiley, published online}, BOOKTITLE = {Encyclopedia of Computational Mechanics Second Edition}, EDITOR = {E.~Stein and R.~de Borst and T. J. R.~Hughes}, SERIES = {Part 2 Fluids}, DOI = {10.1002/9781119176817.ecm2069}, ISBN = {9781119003793} }

[ 9]

Y. Bazilevs, K. Takizawa, T.E. Tezduyar, M.-C. Hsu, N. Kostov, and S. McIntyre, “Computational wind-turbine analysis with the ALE-VMS and ST-VMS methods”, Numerical Simulations of Coupled Problems in Engineering, 33 (2014) 355–386, 10.1007/978-3-319-06136-8_14
Times Cited in Scopus: 1
@INCOLLECTION{Bazilevs14b, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar and Ming-Chen Hsu and N.~Kostov and S.~McIntyre}, TITLE = {Computational Wind-Turbine Analysis with the {ALE-VMS} and {ST-VMS} Methods}, VOLUME = {33}, YEAR = {2014}, PUBLISHER = {Springer}, BOOKTITLE = {Numerical Simulations of Coupled Problems in Engineering}, EDITOR = {S. R.~Idelsohn}, PAGES = {355–386}, SERIES = {Computational Methods in Applied Sciences}, DOI = {10.1007/978-3-319-06136-8_14}, ISBN = {978-3-319-06135-1} } Abstract:
We provide an overview of the aerodynamic and FSI analysis of wind turbines the first three authors’ teams carried out in recent years with the ALE-VMS and ST-VMS methods. The ALE-VMS method is the variational multiscale version of the Arbitrary Lagrangian-Eulerian (ALE) method. The VMS components are from the residual-based VMS (RBVMS) method. The ST-VMS method is the VMS version of the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) method. The techniques complementing these core methods include weak enforcement of the essential boundary conditions, NURBS-based isogeometric analysis, using NURBS basis functions in temporal representation of the rotor motion, mesh motion and also in remeshing, rotation representation with constant angular velocity, Kirchhoff-Love shell modeling of the rotor-blade structure, and full FSI coupling. The analysis cases include the aerodynamics of wind-turbine rotor and tower and the FSI that accounts for the deformation of the rotor blades. The specific wind turbines considered are NREL 5MW, NREL Phase VI and Micon 65/13M, all at full scale, and our analysis for NREL Phase VI and Micon 65/13M includes comparison with the experimental data.

[ 8]

K. Takizawa, Y. Bazilevs, T.E. Tezduyar, M.-C. Hsu, O. Øiseth, K.M. Mathisen, N. Kostov, and S. McIntyre, “Computational engineering analysis and design with ALE-VMS and ST methods”, Numerical Simulations of Coupled Problems in Engineering, 33 (2014) 321–353, 10.1007/978-3-319-06136-8_13
Times Cited in Scopus: 5
@INCOLLECTION{Takizawa14l, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and Ming-Chen Hsu and O.~\O{}iseth and K. M.~Mathisen and N.~Kostov and S.~McIntyre}, TITLE = {Computational Engineering Analysis and Design with {ALE-VMS} and {ST} Methods}, VOLUME = {33}, YEAR = {2014}, PUBLISHER = {Springer}, BOOKTITLE = {Numerical Simulations of Coupled Problems in Engineering}, EDITOR = {S. R.~Idelsohn}, PAGES = {321–353}, SERIES = {Computational Methods in Applied Sciences}, DOI = {10.1007/978-3-319-06136-8_13}, ISBN = {978-3-319-06135-1} } Abstract:
Flows with moving interfaces include fluid-structure interaction (FSI) and quite a few other classes of problems, have an important place in engineering analysis and design, and pose significant computational challenges. Bringing solution and analysis to them motivated the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) method and also the variational multiscale version of the Arbitrary Lagrangian-Eulerian method (ALE-VMS). These two methods and their improved versions have been applied to a diverse set of challenging problems with a common core computational technology need. The classes of problems solved include free-surface and two-fluid flows, fluid-object and fluid-particle interaction, FSI, and flows with solid surfaces in fast, linear or rotational relative motion. Some of the most challenging FSI problems, including parachute FSI, wind-turbine FSI and arterial FSI, are being solved and analyzed with the DSD/SST and ALE-VMS methods as core technologies. Better accuracy and improved turbulence modeling were brought with the recently-introduced VMS version of the DSD/SST method, which is called DSD/SST-VMST (also ST-VMS). In specific classes of problems, such as parachute FSI, arterial FSI, ship hydrodynamics, fluid-object interaction, aerodynamics of flapping wings, and wind-turbine aerodynamics and FSI, the scope and accuracy of the modeling were increased with the special ALE-VMS and ST techniques targeting each of those classes of problems. This article provides an overview of how the core and special ALE-VMS and ST techniques are used in computational engineering analysis and design. The article includes an overview of three of the special ALE-VMS and ST techniques, which are just a few examples of the many special techniques that complement the core methods. The impact of the ALE-VMS and ST methods in engineering analysis and design are shown with examples of challenging problems solved and analyzed in parachute FSI, arterial FSI, ship hydrodynamics, aerodynamics of flapping wings, wind-turbine aerodynamics, and bridge-deck aerodynamics and vortex-induced vibrations.

[ 7]

K. Takizawa, Y. Bazilevs, T.E. Tezduyar, C.C. Long, A.L. Marsden, and K. Schjodt, “Patient-specific cardiovascular fluid mechanics analysis with the ST and ALE-VMS methods”, Numerical Simulations of Coupled Problems in Engineering, 33 (2014) 71–102, 10.1007/978-3-319-06136-8_4
Times Cited in Scopus: 8
@INCOLLECTION{Takizawa14k, AUTHOR = {K.~Takizawa and Y.~Bazilevs and T. E.~Tezduyar and C. C.~Long and A. L.~Marsden and K.~Schjodt}, TITLE = {Patient-Specific Cardiovascular Fluid Mechanics Analysis with the {ST} and {ALE-VMS} Methods}, VOLUME = {33}, YEAR = {2014}, PUBLISHER = {Springer}, BOOKTITLE = {Numerical Simulations of Coupled Problems in Engineering}, EDITOR = {S. R.~Idelsohn}, PAGES = {71–102}, SERIES = {Computational Methods in Applied Sciences}, DOI = {10.1007/978-3-319-06136-8_4}, ISBN = {978-3-319-06135-1} } Abstract:
This chapter provides an overview of how patient-specific cardiovascular fluid mechanics analysis, including fluid-structure interaction (FSI), can be carried out with the space-time (ST) and Arbitrary Lagrangian-Eulerian (ALE) techniques developed by the first three authors’ research teams. The core methods are the ALE-based variational multiscale (ALE-VMS) method, the Deforming-Spatial-Domain/Stabilized ST formulation, and the stabilized ST FSI technique. A good number of special techniques targeting cardiovascular fluid mechanics have been developed to be used with the coremethods. These include (i) arterial-surface extraction and boundary condition techniques, (ii) techniques for using variable arterialwall thickness, (iii) methods for calculating an estimated zero-pressure arterial geometry, (iv) techniques for prestressing of the blood vessel wall, (v) mesh generation techniques for building layers of refined fluid mechanics mesh near the arterial walls, (vi) a special mapping technique for specifying the velocity profile at an inflow boundary with non-circular shape, (vii) a scaling technique for specifying a more realistic volumetric flow rate, (viii) techniques for the projection of fluid-structure interface stresses, (ix) a recipe for pre-FSI computations that improve the convergence of the FSI computations, (x) the Sequentially-Coupled Arterial FSI technique and its multiscale versions, (xi) techniques for calculation of the wall shear stress (WSS) and oscillatory shear index (OSI), (xii) methods for stent modeling and mesh generation, (xiii) methods for calculation of the particle residence time, and (xiv) methods for an estimated element-based zero-stress state for the artery. Here we provide an overview of the special techniques for stent modeling and mesh generation and calculation of the residence time with application to pulsatile ventricular assist device (PVAD). We provide references for some of the other special techniques. With results from earlier computations, we show how the core and special techniques work.

[ 6]

K. Takizawa and T.E. Tezduyar, “Fluid–structure interaction modeling of patient-specific cerebral aneurysms”, Visualization and Simulation of Complex Flows in Biomedical Engineering, 12 (2014) 25–45, 10.1007/978-94-007-7769-9_2
Times Cited in Scopus: 4
@INCOLLECTION{Takizawa12y, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {Fluid–Structure Interaction Modeling of Patient-Specific Cerebral Aneurysms}, VOLUME = {12}, YEAR = {2014}, PUBLISHER = {Springer}, BOOKTITLE = {Visualization and Simulation of Complex Flows in Biomedical Engineering}, EDITOR = {R.~Lima and Y.~Imai and T.~Ishikawa and M.S.N.~Oliveira}, PAGES = {25–45}, SERIES = {Lecture Notes in Computational Vision and Biomechanics}, DOI = {10.1007/978-94-007-7769-9_2}, ISBN = {978-94-007-7768-2} } Abstract:
We provide an overview of the special techniques developed earlier by the Team for Advanced Flow Simulation and Modeling (TwAFSM) for fluid–structure interaction (FSI) modeling of patient-specific cerebral aneurysms. The core FSI techniques are the Deforming-Spatial-Domain/Stabilized Space– Time formulation and the stabilized space–time FSI technique. The special techniques include techniques for calculating an estimated zero-pressure arterial geometry, a special mapping technique for specifying the velocity profile at an inflow boundary with non-circular shape, techniques for using variable arterial wall thickness, mesh generation techniques for building layers of refined fluid mechanics mesh near the arterial walls, a recipe for pre-FSI computations that improve the convergence of the FSI computations, techniques for calculation of the wall shear stress and oscillatory shear index, and arterial-surface extraction and boundary condition techniques. We show, with results from earlier computations, how these techniques work. We also describe the arterial FSI techniques developed and implemented recently by the TwAFSM and present a sample from a wide set of patient-specific cerebral-aneurysm models we computed recently.

[ 5]

K. Takizawa, K. Schjodt, A. Puntel, N. Kostov, and T.E. Tezduyar, “Patient-specific computational fluid mechanics of cerebral arteries with aneurysm and stent”, Multiscale Simulations and Mechanics of Biological Materials (2013) 119–147
@INCOLLECTION{Takizawa12q, AUTHOR = {K.~Takizawa and K.~Schjodt and A.~Puntel and N.~Kostov and T. E.~Tezduyar}, TITLE = {Patient-Specific Computational Fluid Mechanics of Cerebral Arteries with Aneurysm and Stent}, VOLUME = {None}, YEAR = {2013}, PUBLISHER = {Wiley}, BOOKTITLE = {Multiscale Simulations and Mechanics of Biological Materials}, EDITOR = {S.~Li and D.~Qian}, PAGES = {119–147}, SERIES = {None}, DOI = {None}, ISBN = {978-1-118-35079-9} }

[ 4]

K. Takizawa, C. Moorman, S. Wright, and T.E. Tezduyar, “Computer modeling and analysis of the Orion spacecraft parachutes”, Fluid–Structure Interaction II – Modelling, Simulation, Optimization, 73 (2010) 53–81, 10.1007/978-3-642-14206-2_3
Times Cited in Scopus: 5
@INCOLLECTION{Takizawa09g, AUTHOR = {K.~Takizawa and C.~Moorman and S.~Wright and T. E.~Tezduyar}, TITLE = {Computer Modeling and Analysis of the {O}rion Spacecraft Parachutes}, VOLUME = {73}, YEAR = {2010}, PUBLISHER = {Springer}, BOOKTITLE = {Fluid–Structure Interaction II — Modelling, Simulation, Optimization}, EDITOR = {Hans-Joachim Bungartz and M.~Mehl and M.~Schafer}, PAGES = {53–81}, SERIES = {Lecture Notes in Computational Science and Engineering}, DOI = {10.1007/978-3-642-14206-2_3}, ISBN = {978-3-642-14206-2} } Abstract:
We focus on fluid-structure interaction (FSI) modeling of the ringsail parachutes to be used with the Orion spacecraft. The geometric porosity of the ringsail parachutes with ring gaps and sail slits is one of the major computational challenges involved in FSI modeling. We address the computational challenges with the latest techniques developed by the Team for Advanced Flow Simulation and Modeling (T Black star AFSM) in conjunction with the Stabilized Space-Time Fluid-Structure Interaction (SSTFSI) technique. We investigate the performance of the three possible design configurations of the parachute canopy, carry out parametric studies on using an over-inflation control line (OICL) intended for enhancing the parachute performance, discuss rotational periodicity techniques for improving the geometric-porosity modeling and for computing good starting conditions for parachute clusters, and report results from preliminary FSI computations for parachute clusters. We also present a stability and accuracy analysis for the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation, which is the core numerical technology of the SSTFSI technique. © 2011 Springer.

[ 3]

T.E. Tezduyar, K. Takizawa, and J. Christopher, “Multiscale Sequentially-Coupled Arterial Fluid–Structure Interaction (SCAFSI) technique”, International Workshop on Fluid–Structure Interaction — Theory, Numerics and Applications (2009) 231–252
@INCOLLECTION{Tezduyar09a, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and J.~Christopher}, TITLE = {Multiscale {S}equentially-{C}oupled {A}rterial {F}luid–{S}tructure {I}nteraction ({SCAFSI}) Technique}, YEAR = {2009}, PUBLISHER = {Kassel University Press}, BOOKTITLE = {International Workshop on Fluid–Structure Interaction — Theory, Numerics and Applications}, EDITOR = {S.~Hartmann and A.~Meister and M.~Schafer and S.~Turek}, PAGES = {231–252}, ISBN = {978-3-89958-666-4} }

[ 2]

T. Yabe, Y. Ogata, and K. Takizawa, “Recent advances of multi-phase flow computation with the adaptive Soroban-grid cubic interpolated propagation (CIP) method”, Computational Fluid Dynamics 2006 (2009) 29–43, 10.1007/978-3-540-92779-2_3
@INCOLLECTION{Yabe09b, AUTHOR = {T.~Yabe and Y.~Ogata and K.~Takizawa}, TITLE = {Recent Advances of Multi-phase Flow Computation with the Adaptive {S}oroban-grid Cubic Interpolated Propagation ({CIP}) Method}, VOLUME = {None}, YEAR = {2009}, PUBLISHER = {Springer}, BOOKTITLE = {Computational Fluid Dynamics 2006}, EDITOR = {Herman Deconinck and E. Dick}, PAGES = {29–43}, DOI = {10.1007/978-3-540-92779-2_3}, ISBN = {978-3-540-92778-5} }

[ 1]

T. Yabe, K. Takizawa, F. Xiao, and A. Ikebata, “Universal solver CIP for all phases of matter”, Recent Advances in Scientific Computing and Partial Differential Equations, 330 (2003) 203–222
@INCOLLECTION{Yabe04a, AUTHOR = {T.~Yabe and K.~Takizawa and F.~Xiao and A.~Ikebata}, TITLE = {Universal Solver {CIP} for All Phases of Matter}, VOLUME = {330}, YEAR = {2003}, PUBLISHER = {American Mathematical Society}, BOOKTITLE = {Recent Advances in Scientific Computing and Partial Differential Equations}, EDITOR = {S. Y.~Cheng and Chi-Wang~Shu and T.~Tang}, PAGES = {203–222}, SERIES = {Contemporary Mathematics}, ISBN = {0821831550} }

Invited Conference Papers

[42]

K. Takizawa, D. Montes, M. Fritze, S. McIntyre, J. Boben, Y. Tsutsui, and T.E. Tezduyar, “FSI modeling of spacecraft parachute dynamics and cover separation”, Extended Abstracts of JSME 25th Computational Mechanics Division Conference (2012)
@INPROCEEDINGS{Takizawa12v, AUTHOR = {K.~Takizawa and D.~Montes and M.~Fritze and S.~McIntyre and J.~Boben and Y.~Tsutsui and T. E.~Tezduyar}, TITLE = {{FSI} Modeling of Spacecraft Parachute Dynamics and Cover Separation}, YEAR = {2012}, BOOKTITLE = {Extended Abstracts of JSME 25th Computational Mechanics Division Conference}, ADDRESS = {Kobe, Japan} }

[41]

K. Takizawa, H. Takagi, and T.E. Tezduyar, “Effect of longitudinal prestress in arterial FSI”, Extended Abstracts of JSME 25th Computational Mechanics Division Conference (2012)
@INPROCEEDINGS{Takizawa12u, AUTHOR = {K.~Takizawa and H.~Takagi and T. E.~Tezduyar}, TITLE = {Effect of Longitudinal Prestress in Arterial {FSI}}, YEAR = {2012}, BOOKTITLE = {Extended Abstracts of JSME 25th Computational Mechanics Division Conference}, ADDRESS = {Kobe, Japan} }

[40]

K. Takizawa and T.E. Tezduyar, “Space–time computational FSI techniques — Special technologies”, Lecture Notes on Finite Elements in Flow Problems — Basics and Applications (2012)
@INPROCEEDINGS{Takizawa12t, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {Space–Time Computational {FSI} Techniques — {S}pecial Technologies}, YEAR = {2012}, BOOKTITLE = {Lecture Notes on Finite Elements in Flow Problems — Basics and Applications}, ADDRESS = {Tokyo, Japan} }

[39]

T.E. Tezduyar and K. Takizawa, “Space–time computational FSI techniques — Core technologies”, Lecture Notes on Finite Elements in Flow Problems — Basics and Applications (2012)
@INPROCEEDINGS{Tezduyar12i, AUTHOR = {T. E.~Tezduyar and K.~Takizawa}, TITLE = {Space–Time Computational {FSI} Techniques — {C}ore Technologies}, YEAR = {2012}, BOOKTITLE = {Lecture Notes on Finite Elements in Flow Problems — Basics and Applications}, ADDRESS = {Tokyo, Japan} }

[38]

K. Takizawa and T.E. Tezduyar, “Space–time method and space–time VMS technique”, Lecture Notes on Finite Elements in Flow Problems — Basics and Applications (2012)
@INPROCEEDINGS{Takizawa12s, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {Space–Time Method and Space–Time {VMS} Technique}, YEAR = {2012}, BOOKTITLE = {Lecture Notes on Finite Elements in Flow Problems — Basics and Applications}, ADDRESS = {Tokyo, Japan} }

[37]

T.E. Tezduyar and K. Takizawa, “Stabilized formulations — Special techniques”, Lecture Notes on Finite Elements in Flow Problems — Basics and Applications (2012)
@INPROCEEDINGS{Tezduyar12h, AUTHOR = {T. E.~Tezduyar and K.~Takizawa}, TITLE = {Stabilized Formulations — {S}pecial Techniques}, YEAR = {2012}, BOOKTITLE = {Lecture Notes on Finite Elements in Flow Problems — Basics and Applications}, ADDRESS = {Tokyo, Japan} }

[36]

K. Takizawa and T.E. Tezduyar, “FSI coupling techniques”, Lecture Notes on Finite Elements in Flow Problems — Basics and Applications (2012)
@INPROCEEDINGS{Takizawa12r, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {{FSI} Coupling Techniques}, YEAR = {2012}, BOOKTITLE = {Lecture Notes on Finite Elements in Flow Problems — Basics and Applications}, ADDRESS = {Tokyo, Japan} }

[35]

T.E. Tezduyar and K. Takizawa, “Mesh update methods for flows with moving interfaces”, Lecture Notes on Finite Elements in Flow Problems — Basics and Applications (2012)
@INPROCEEDINGS{Tezduyar12g, AUTHOR = {T. E.~Tezduyar and K.~Takizawa}, TITLE = {Mesh Update Methods for Flows with Moving Interfaces}, YEAR = {2012}, BOOKTITLE = {Lecture Notes on Finite Elements in Flow Problems — Basics and Applications}, ADDRESS = {Tokyo, Japan} }

[34]

T.E. Tezduyar and K. Takizawa, “Introduction to computational fluid mechanics with computer-generated movies and pictures”, Lecture Notes on Finite Elements in Flow Problems — Basics and Applications (2012)
@INPROCEEDINGS{Tezduyar12f, AUTHOR = {T. E.~Tezduyar and K.~Takizawa}, TITLE = {Introduction to Computational Fluid Mechanics with Computer-Generated Movies and Pictures}, YEAR = {2012}, BOOKTITLE = {Lecture Notes on Finite Elements in Flow Problems — Basics and Applications}, ADDRESS = {Tokyo, Japan} }

[33]

K. Takizawa, T. Spielman, and T.E. Tezduyar, “Dynamical analysis of parachute clusters”, Extended Abstracts of JSME-CMD International Computational Mechanics Symposium 2012 (2012)
@INPROCEEDINGS{Takizawa12p, AUTHOR = {K.~Takizawa and T.~Spielman and T. E.~Tezduyar}, TITLE = {Dynamical Analysis of Parachute Clusters}, YEAR = {2012}, BOOKTITLE = {Extended Abstracts of JSME-CMD International Computational Mechanics Symposium 2012}, ADDRESS = {Kobe, Japan} }

[32]

K. Takizawa, T. Brummer, K. Schjodt, N. Kostov, A. Puntel, H. Takagi, and T.E. Tezduyar, “Patient-specific modeling of fluid–structure interaction and stenting in cerebral arteries with aneurysm”, Extended Abstracts of JSME-CMD International Computational Mechanics Symposium 2012 (2012)
@INPROCEEDINGS{Takizawa12o, AUTHOR = {K.~Takizawa and T.~Brummer and K.~Schjodt and N.~Kostov and A.~Puntel and H.~Takagi and T. E.~Tezduyar}, TITLE = {Patient-Specific Modeling of Fluid–Structure Interaction and Stenting in Cerebral Arteries with Aneurysm}, YEAR = {2012}, BOOKTITLE = {Extended Abstracts of JSME-CMD International Computational Mechanics Symposium 2012}, ADDRESS = {Kobe, Japan} }

[31]

T.E. Tezduyar and K. Takizawa, “Space-time computational fluid-structure interaction techniques”, Proceedings of the 19th National Computational Fluid Dynamics Conference (2012)
@INPROCEEDINGS{Tezduyar12e, AUTHOR = {T. E.~Tezduyar and K.~Takizawa}, TITLE = {Space-Time Computational Fluid-Structure Interaction Techniques}, YEAR = {2012}, BOOKTITLE = {Proceedings of the 19th National Computational Fluid Dynamics Conference}, ADDRESS = {Penghu, Taiwan} }

[30]

K. Takizawa, B. Henicke, A. Puntel, N. Kostov, and T.E. Tezduyar, “Space–time computational techniques for the aerodynamics of flapping locust wings”, Proceedings of International Workshop on Future of CFD and Aerospace Sciences (2012)
@INPROCEEDINGS{Takizawa12m, AUTHOR = {K.~Takizawa and B.~Henicke and A.~Puntel and N.~Kostov and T. E.~Tezduyar}, TITLE = {Space–Time Computational Techniques for the Aerodynamics of Flapping Locust Wings}, YEAR = {2012}, BOOKTITLE = {Proceedings of International Workshop on Future of {CFD} and Aerospace Sciences}, ADDRESS = {Kobe, Japan} }

[29]

K. Takizawa, K. Schjodt, A. Puntel, N. Kostov, H. Takagi, S. Asada, and T.E. Tezduyar, “Patient-specific modeling of cerebral aneurysms with FSI and stent”, Proceedings of 17th Japan Society of Computational Engineering and Science Conference (2012)
@INPROCEEDINGS{Takizawa12l, AUTHOR = {K.~Takizawa and K.~Schjodt and A.~Puntel and N.~Kostov and H.~Takagi and S.~Asada and T. E.~Tezduyar}, TITLE = {Patient-Specific Modeling of Cerebral Aneurysms with {FSI} and Stent}, YEAR = {2012}, BOOKTITLE = {Proceedings of 17th Japan Society of Computational Engineering and Science Conference}, ADDRESS = {Kyoto, Japan} }

[28]

K. Takizawa, M. Fritze, D. Montes, S. McIntyre, J. Boben, S. Tabata, Y. Tsutsui, and T.E. Tezduyar, “Computational modeling of parachute fluid–structure interaction”, Proceedings of 17th Japan Society of Computational Engineering and Science Conference (2012)
@INPROCEEDINGS{Takizawa12k, AUTHOR = {K.~Takizawa and M.~Fritze and D.~Montes and S.~McIntyre and J.~Boben and S.~Tabata and Y.~Tsutsui and T. E.~Tezduyar}, TITLE = {Computational Modeling of Parachute Fluid–Structure Interaction}, YEAR = {2012}, BOOKTITLE = {Proceedings of 17th Japan Society of Computational Engineering and Science Conference}, ADDRESS = {Kyoto, Japan} }

[27]

K. Takizawa, T.E. Tezduyar, and Y. Bazilevs, “FSI coupling techniques and iterative solution methods”, Lectures on Computational Fluid–Structure Interaction (2012)
@INPROCEEDINGS{Takizawa12j, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and Y.~Bazilevs}, TITLE = {{FSI} Coupling Techniques and Iterative Solution Methods}, YEAR = {2012}, BOOKTITLE = {Lectures on Computational Fluid–Structure Interaction}, ADDRESS = {Tokyo, Japan} }

[26]

T.E. Tezduyar, K. Takizawa, and Y. Bazilevs, “Mesh update methods for computation of flows with moving boundaries and interfaces”, Lectures on Computational Fluid–Structure Interaction (2012)
@INPROCEEDINGS{Tezduyar12d, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and Y.~Bazilevs}, TITLE = {Mesh Update Methods for Computation of Flows With Moving Boundaries and Interfaces}, YEAR = {2012}, BOOKTITLE = {Lectures on Computational Fluid–Structure Interaction}, ADDRESS = {Tokyo, Japan} }

[25]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “Introductory computational structural mechanics”, Lectures on Computational Fluid–Structure Interaction (2012)
@INPROCEEDINGS{Bazilevs12c, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Introductory Computational Structural Mechanics}, YEAR = {2012}, BOOKTITLE = {Lectures on Computational Fluid–Structure Interaction}, ADDRESS = {Tokyo, Japan} }

[24]

K. Takizawa, T.E. Tezduyar, and Y. Bazilevs, “Space–time method and Space–Time VMS technique”, Lectures on Computational Fluid–Structure Interaction (2012)
@INPROCEEDINGS{Takizawa12i, AUTHOR = {K.~Takizawa and T. E.~Tezduyar and Y.~Bazilevs}, TITLE = {Space–Time Method and {S}pace–{T}ime {VMS} Technique}, YEAR = {2012}, BOOKTITLE = {Lectures on Computational Fluid–Structure Interaction}, ADDRESS = {Tokyo, Japan} }

[23]

Y. Bazilevs, K. Takizawa, and T.E. Tezduyar, “ALE method and ALE-VMS technique”, Lectures on Computational Fluid–Structure Interaction (2012)
@INPROCEEDINGS{Bazilevs12b, AUTHOR = {Y.~Bazilevs and K.~Takizawa and T. E.~Tezduyar}, TITLE = {{ALE} Method and {ALE-VMS} Technique}, YEAR = {2012}, BOOKTITLE = {Lectures on Computational Fluid–Structure Interaction}, ADDRESS = {Tokyo, Japan} }

[22]

T.E. Tezduyar, K. Takizawa, and Y. Bazilevs, “Stabilized formulations in computational fluid mechanics and fluid–structure interaction”, Lectures on Computational Fluid–Structure Interaction (2012)
@INPROCEEDINGS{Tezduyar12c, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and Y.~Bazilevs}, TITLE = {Stabilized Formulations in Computational Fluid Mechanics and Fluid–Structure Interaction}, YEAR = {2012}, BOOKTITLE = {Lectures on Computational Fluid–Structure Interaction}, ADDRESS = {Tokyo, Japan} }

[21]

K. Takizawa and T.E. Tezduyar, “Space–time computational FSI techniques — Special technologies”, Lectures on Computational Fluid–Structure Interaction (2012)
@INPROCEEDINGS{Takizawa12h, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {Space–Time Computational {FSI} Techniques — {S}pecial Technologies}, YEAR = {2012}, BOOKTITLE = {Lectures on Computational Fluid–Structure Interaction}, ADDRESS = {Tokyo, Japan} }

[20]

T.E. Tezduyar and K. Takizawa, “Space–time computational FSI techniques — Core technologies”, Lectures on Computational Fluid–Structure Interaction (2012)
@INPROCEEDINGS{Tezduyar12b, AUTHOR = {T. E.~Tezduyar and K.~Takizawa}, TITLE = {Space–Time Computational {FSI} Techniques — {C}ore Technologies}, YEAR = {2012}, BOOKTITLE = {Lectures on Computational Fluid–Structure Interaction}, ADDRESS = {Tokyo, Japan} }

[19]

T.E. Tezduyar, K. Takizawa, and S. Wright, “Fluid–structure interaction modeling of spacecraft parachutes”, Extended Abstracts of the 61st National Congress of Theoretical and Applied Mechanics (2012)
@INPROCEEDINGS{Tezduyar12a, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and S.~Wright}, TITLE = {Fluid–Structure Interaction Modeling of Spacecraft Parachutes}, YEAR = {2012}, BOOKTITLE = {Extended Abstracts of the 61st National Congress of Theoretical and Applied Mechanics}, ADDRESS = {Tokyo, Japan} }

[18]

K. Takizawa, S. Asada, N. Kostov, and T.E. Tezduyar, “Space–time formulation of fully-coupled fluid–object interaction”, Proceedings of the 25th Computational Fluid Dynamics Conference (2011)
@INPROCEEDINGS{Takizawa11p, AUTHOR = {K.~Takizawa and S.~Asada and N.~Kostov and T. E.~Tezduyar}, TITLE = {Space–Time Formulation of Fully-Coupled Fluid–Object Interaction}, YEAR = {2011}, BOOKTITLE = {Proceedings of the 25th Computational Fluid Dynamics Conference}, ADDRESS = {Osaka, Japan} }

[17]

K. Takizawa, M. Fritze, T. Spielman, C. Moorman, S. Tabata, and T.E. Tezduyar, “Space–time FSI computation of parachute disreefing”, Proceedings of the 25th Computational Fluid Dynamics Conference (2011)
@INPROCEEDINGS{Takizawa11o, AUTHOR = {K.~Takizawa and M.~Fritze and T.~Spielman and C.~Moorman and S.~Tabata and T. E.~Tezduyar}, TITLE = {Space–Time {FSI} Computation of Parachute Disreefing}, YEAR = {2011}, BOOKTITLE = {Proceedings of the 25th Computational Fluid Dynamics Conference}, ADDRESS = {Osaka, Japan} }

[16]

K. Takizawa, S. Wright, J. Christopher, and T.E. Tezduyar, “Multiscale sequentially-coupled FSI computation in parachute modeling”, Structural Membranes 2011 (2011)
Times Cited in Scopus: 1
@INPROCEEDINGS{Takizawa11l, AUTHOR = {K.~Takizawa and S.~Wright and J.~Christopher and T. E.~Tezduyar}, TITLE = {Multiscale Sequentially-Coupled {FSI} Computation in Parachute Modeling}, YEAR = {2011}, PUBLISHER = {CIMNE}, BOOKTITLE = {Structural Membranes 2011}, EDITOR = {E.~Onate and B.~Kroplin and Kai-Uwe Bletzinger}, ADDRESS = {Barcelona, Spain} } Abstract:
We describe how the spatially multiscale Sequentially-Coupled Fluid-Structure Interaction (SCFSI) techniques we have developed, specifically the “SCFSI M2C”, which is spatially multiscale for the structural mechanics part, can be used for increasing the accuracy of the membrane and cable structural mechanics solution in parachute FSI computations. The SCFSI M2C technique is used here in conjunction with the Stabilized Space-Time FSI (SSTFSI) technique, which was developed and improved over the years by the Team for Advanced Flow Simulation and Modeling (T *AFSM) and serves as the core numerical technology, and a number of special parachute FSI techniques developed by the T *AFSM in conjunction with the SSTFSI technique.

[15]

K. Takizawa, T. Spielman, and T.E. Tezduyar, “Space–time FSI modeling of ringsail parachute clusters”, Structural Membranes 2011 (2011)
@INPROCEEDINGS{Takizawa11k, AUTHOR = {K.~Takizawa and T.~Spielman and T. E.~Tezduyar}, TITLE = {Space–Time {FSI} Modeling of Ringsail Parachute Clusters}, YEAR = {2011}, PUBLISHER = {CIMNE}, BOOKTITLE = {Structural Membranes 2011}, EDITOR = {E.~Onate and B.~Kroplin and Kai-Uwe Bletzinger}, ADDRESS = {Barcelona, Spain} } Abstract:
The computational challenges posed by fluid-structure interaction (FSI) modeling of ringsail parachute clusters include the lightness of the membrane and cable structure of the canopy compared to the air masses involved in the parachute dynamics, geometric complexities created by the construction of the canopy from “rings” and “sails” with hundreds of ring gaps and sail slits, and the contact between the parachutes. The Team for Advanced Flow Simulation and Modeling (T *AFSM) has successfully addressed these computational challenges with the Stabilized Space-Time FSI technique (SSTFSI), which was developed and improved over the years by the T *AFSM and serves as the core numerical technology, and a number of special techniques developed in conjunction with the SSTFSI. We present the results obtained with the FSI computation of parachute clusters and the related dynamical analysis.

[14]

K. Takizawa, T. Spielman, and T.E. Tezduyar, “Fluid–structure interaction modeling of ringsail parachute clusters”, Recent Progress in Fluid Dynamics Research, Proceedings of the Sixth International Conference on Fluid Mechanics (2011), 10.1063/1.3651825
@INPROCEEDINGS{Takizawa11j, AUTHOR = {K.~Takizawa and T.~Spielman and T. E.~Tezduyar}, TITLE = {Fluid–Structure Interaction Modeling of Ringsail Parachute Clusters}, YEAR = {2011}, PUBLISHER = {American Institute of Physics}, BOOKTITLE = {Recent Progress in Fluid Dynamics Research, Proceedings of the Sixth International Conference on Fluid Mechanics}, ADDRESS = {Guangzhou, China}, SERIES = {AIP Conf. Proc. Vol 1376, 7–11}, DOI = {10.1063/1.3651825} } Abstract:
The team for advanced flow simulation and modeling (TBlack starAFSM) has successfully addressed many of the computational challenges involved in fluid-structure interaction (FSI) modeling of ringsail parachutes, including the geometric complexities, and recently started addressing the challenges related to the contact between the parachutes of a cluster. This is being accomplished with the stabilized space-time FSI technique, which was developed by the TBlack starAFSM and serves as the core numerical technology, and the special techniques developed by the TBlack starAFSM. We present the results obtained with the FSI computation of parachute clusters and the related dynamical analysis. © 2011 American Institute of Physics.

[13]

K. Takizawa, T. Spielman, and T.E. Tezduyar, “Space–time FSI modeling and dynamical analysis of ringsail parachute clusters”, Coupled Problems 2011 (2011)
@INPROCEEDINGS{Takizawa11i, AUTHOR = {K.~Takizawa and T.~Spielman and T. E.~Tezduyar}, TITLE = {Space–Time {FSI} Modeling and Dynamical Analysis of Ringsail Parachute Clusters}, YEAR = {2011}, PUBLISHER = {CIMNE}, BOOKTITLE = {Coupled Problems 2011}, EDITOR = {M.~Papadrakakis and E.~Onate and B.~Schrefler}, ADDRESS = {Barcelona, Spain} } Abstract:
Computer modeling of ringsail parachute clusters involves fluid-structure interaction (FSI) between the parachute canopy and the air, geometric complexities created by the construction of the parachute from “rings” and “sails” with hundreds of gaps and slits, and the contact between the parachutes. The Team for Advanced Flow Simulation and Modeling (T*AFSM) has successfully addressed the computational challenges related to the FSI and geometric complexities, and recently started addressing the challenges related to the contact between the parachutes of a cluster. This is being accomplished with the Stabilized Space-Time FSI technique, which was developed and improved over the years by the T*AFSM and serves as the core numerical technology, and the special techniques developed by the T*AFSM to deal with the geometric complexities and the contact between parachutes. We present the results obtained with the FSI computation of parachute clusters and the related dynamical analysis.

[12]

K. Takizawa and T.E. Tezduyar, “Multiscale space–time computation techniques”, Coupled Problems 2011 (2011)
@INPROCEEDINGS{Takizawa11h, AUTHOR = {K.~Takizawa and T. E.~Tezduyar}, TITLE = {Multiscale Space–Time Computation Techniques}, YEAR = {2011}, PUBLISHER = {CIMNE}, BOOKTITLE = {Coupled Problems 2011}, EDITOR = {M.~Papadrakakis and E.~Onate and B.~Schrefler}, ADDRESS = {Barcelona, Spain} } Abstract:
A number of multiscale space-time techniques have been developed recently by the Team for Advanced Flow Simulation and Modeling (T*AFSM) for fluid-structure interaction computations. As part of that, we have introduced a space-time version of the residual-based variational multiscale method. It has been designed in the context of the Deforming-Spatial-Domain/Stabilized Space-Time formulation, which was developed earlier by the T*AFSM for computation of flow problems with moving boundaries and interfaces. We describe this multiscale space-time technique, and present results from test computations.

[11]

K. Takizawa, T. Brummer, T.E. Tezduyar, and P.R. Chen, “Comparative patient-specific FSI modeling of cerebral aneurysms”, Coupled Problems 2011 (2011)
@INPROCEEDINGS{Takizawa11g, AUTHOR = {K.~Takizawa and T.~Brummer and T. E.~Tezduyar and P. R.~Chen}, TITLE = {Comparative Patient-Specific {FSI} Modeling of Cerebral Aneurysms}, YEAR = {2011}, PUBLISHER = {CIMNE}, BOOKTITLE = {Coupled Problems 2011}, EDITOR = {M.~Papadrakakis and E.~Onate and B.~Schrefler}, ADDRESS = {Barcelona, Spain} } Abstract:
We consider a total of ten cases, at three different locations, half of which ruptured sometime after the images were taken. We use the stabilized space-time FSI technique developed by the Team for Advanced Flow Simulation and Modeling, together with a number of special techniques targeting arterial FSI modeling. We compare the ten cases based on the wall shear stress, oscillatory shear index, and the arterial-wall stress. We also investigate how simpler approaches to computer modeling of cerebral aneurysms perform compared to FSI modeling.

[10]

T. Yabe, Y. Ogata, T. Sugimoto, K. Takizawa, and K. Takahashi, “Soroban-Grid CIP method for ocean research and ship design – High performance computing with Earth Simulator -”, Parallel CFD 2009 (2009)
@INPROCEEDINGS{Yabe09a, AUTHOR = {T.~Yabe and Y.~Ogata and T.~Sugimoto and K.~Takizawa and K.~Takahashi}, TITLE = {{S}oroban-{G}rid {CIP} Method for Ocean Research and Ship Design – {H}igh Performance Computing with {E}arth {S}imulator -}, YEAR = {2009}, BOOKTITLE = {Parallel CFD 2009}, ADDRESS = {California, USA} }

[ 9]

M. Manguoglu, K. Takizawa, A.H. Sameh, and T.E. Tezduyar, “Novel solvers for linear systems in computational fluid dynamics”, Marine 2009 (2009)
@INPROCEEDINGS{Manguoglu09a0, AUTHOR = {M.~Manguoglu and K.~Takizawa and A. H.~Sameh and T. E.~Tezduyar}, TITLE = {Novel Solvers for Linear Systems in Computational Fluid Dynamics}, YEAR = {2009}, PUBLISHER = {CIMNE}, BOOKTITLE = {Marine 2009}, EDITOR = {T.~Kvamsdal and B.~Pettersen and P.~Bergan and E.~Onate and J.~Garcia}, ADDRESS = {Barcelona, Spain} }

[ 8]

T.E. Tezduyar, K. Takizawa, J. Christopher, C. Moorman, and S. Wright, “Space–time finite element computation of complex FSI problems”, Coupled Problems 2009 (2009)
@INPROCEEDINGS{Tezduyar09b2, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and J.~Christopher and C.~Moorman and S.~Wright}, TITLE = {Space–Time Finite Element Computation of Complex {FSI} Problems}, YEAR = {2009}, PUBLISHER = {CIMNE}, BOOKTITLE = {Coupled Problems 2009}, EDITOR = {B.~Schrefler and E.~Onate and M.~Papadrakakis}, ADDRESS = {Barcelona, Spain} }

[ 7]

K. Takizawa, J. Christopher, C. Moorman, J. Martin, J. Purdue, T. McPhail, P.R. Chen, J. Warren, and T.E. Tezduyar, “Space–time finite element computation of arterial FSI with patient-specific data”, Coupled Problems 2009 (2009)
@INPROCEEDINGS{Takizawa09c, AUTHOR = {K.~Takizawa and J.~Christopher and C.~Moorman and J.~Martin and J.~Purdue and T.~McPhail and P. R.~Chen and J.~Warren and T. E.~Tezduyar}, TITLE = {Space–Time Finite Element Computation of Arterial {FSI} with Patient-Specific Data}, YEAR = {2009}, PUBLISHER = {CIMNE}, BOOKTITLE = {Coupled Problems 2009}, EDITOR = {B.~Schrefler and E.~Onate and M.~Papadrakakis}, ADDRESS = {Barcelona, Spain} }

[ 6]

K. Takizawa, J. Christopher, C. Moorman, S. Wright, J. Martin, and T.E. Tezduyar, “Fluid–structure interaction modeling of the Orion spacecraft parachutes”, Coupled Problems 2009 (2009)
@INPROCEEDINGS{Takizawa09b, AUTHOR = {K.~Takizawa and J.~Christopher and C.~Moorman and S.~Wright and J.~Martin and T. E.~Tezduyar}, TITLE = {Fluid–Structure Interaction Modeling of the {O}rion Spacecraft Parachutes}, YEAR = {2009}, PUBLISHER = {CIMNE}, BOOKTITLE = {Coupled Problems 2009}, EDITOR = {B.~Schrefler and E.~Onate and M.~Papadrakakis}, ADDRESS = {Barcelona, Spain} }

[ 5]

T.E. Tezduyar, K. Takizawa, and J. Christopher, “Sequentially-coupled FSI technique”, Marine 2009 (2009)
@INPROCEEDINGS{Tezduyar09c, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and J.~Christopher}, TITLE = {Sequentially-Coupled {FSI} Technique}, YEAR = {2009}, PUBLISHER = {CIMNE}, BOOKTITLE = {Marine 2009}, EDITOR = {T.~Kvamsdal and B.~Pettersen and P.~Bergan and E.~Onate and J.~Garcia}, ADDRESS = {Barcelona, Spain} }

[ 4]

T.E. Tezduyar, K. Takizawa, J. Christopher, C. Moorman, and S. Wright, “Interface projection techniques for complex FSI problems”, Marine 2009 (2009)
@INPROCEEDINGS{Tezduyar09b, AUTHOR = {T. E.~Tezduyar and K.~Takizawa and J.~Christopher and C.~Moorman and S.~Wright}, TITLE = {Interface Projection Techniques for Complex {FSI} Problems}, YEAR = {2009}, PUBLISHER = {CIMNE}, BOOKTITLE = {Marine 2009}, EDITOR = {T.~Kvamsdal and B.~Pettersen and P.~Bergan and E.~Onate and J.~Garcia}, ADDRESS = {Barcelona, Spain} }

[ 3]

K. Takizawa, S. Sathe, and T.E. Tezduyar, “Incompressible flow computations with the multi-moment and SUPG/PSPG formulations”, Proceedings of the Third Asian-Pacific Congress on Computational Mechanics (CD-ROM) (2007)
@INPROCEEDINGS{Takizawa07c, AUTHOR = {K.~Takizawa and S.~Sathe and T. E.~Tezduyar}, TITLE = {Incompressible Flow Computations with the Multi-Moment and {SUPG/PSPG} Formulations}, YEAR = {2007}, BOOKTITLE = {Proceedings of the Third Asian-Pacific Congress on Computational Mechanics (CD-ROM)}, ADDRESS = {Kyoto, Japan} }

[ 2]

T. Yabe, K. Takizawa, and T.E. Tezduyar, “Computation of fluid–structure interactions with the CIP method based on adaptive meshless Soroban grids”, Marine 2007 (2007)
@INPROCEEDINGS{Yabe07b, AUTHOR = {T.~Yabe and K.~Takizawa and T. E.~Tezduyar}, TITLE = {Computation of Fluid–Structure Interactions with the {CIP} Method Based on Adaptive Meshless {S}oroban Grids}, YEAR = {2007}, PUBLISHER = {CIMNE}, BOOKTITLE = {Marine 2007}, EDITOR = {E.~Onate and J.~Garcia and P.~Bergan and T.~Kvamsdal}, ADDRESS = {Barcelona, Spain} }

[ 1]

K. Takizawa, K. Tanizawa, T. Yabe, and T.E. Tezduyar, “Computational ship hydrodynamics with the CIP method”, Marine 2007 (2007)
@INPROCEEDINGS{Takizawa07b, AUTHOR = {K.~Takizawa and K.~Tanizawa and T.~Yabe and T. E.~Tezduyar}, TITLE = {Computational Ship Hydrodynamics with the {CIP} Method}, YEAR = {2007}, PUBLISHER = {CIMNE}, BOOKTITLE = {Marine 2007}, EDITOR = {E.~Onate and J.~Garcia and P.~Bergan and T.~Kvamsdal}, ADDRESS = {Barcelona, Spain} }

Conference Papers

[20]

M. Omori, T. Kuraishi, K. Takizawa, and T.E. Tezduyar, “High spatial and temporal resolution computational analysis of flow between an engine cylinder and moving piston”, Proceedings of the 11th Pacific Symposium on Flow Visualization and Image Processing (2017)
@INPROCEEDINGS{Omori17a, AUTHOR = {M.~Omori and T.~Kuraishi and K.~Takizawa and T. E.~Tezduyar}, TITLE = {High Spatial and Temporal Resolution Computational Analysis of Flow Between an Engine Cylinder and Moving Piston}, YEAR = {2017}, BOOKTITLE = {Proceedings of the 11th Pacific Symposium on Flow Visualization and Image Processing}, ADDRESS = {Kumamoto, Japan} }

[19]

H. Hattori, K. Takizawa, T.E. Tezduyar, K. Miyagawa, M. Nomi, M. Isono, H. Uchida, and M. Kawai, “Computational analysis of flow-driven string dynamics in a turbomachinery”, Proceedings of 13th Asian International Conference on Fluid Machinery (2015)
@INPROCEEDINGS{Hattori15a, AUTHOR = {H.~Hattori and K.~Takizawa and T. E.~Tezduyar and K.~Miyagawa and M.~Nomi and M.~Isono and H.~Uchida and M.~Kawai}, TITLE = {Computational Analysis of Flow-Driven String Dynamics in a Turbomachinery}, YEAR = {2015}, BOOKTITLE = {Proceedings of 13th Asian International Conference on Fluid Machinery}, ADDRESS = {Tokyo, Japan}, SERIES = {Paper No. AICFM13-154} }

[18]

Y. Otoguro, T. Terahara, K. Takizawa, T.E. Tezduyar, T. Kuraishi, and H. Hattori, “A higher-order ST-VMS method for turbocharger analysis”, Proceedings of 13th Asian International Conference on Fluid Machinery (2015)
@INPROCEEDINGS{Otoguro15a, AUTHOR = {Y.~Otoguro and T.~Terahara and K.~Takizawa and T. E.~Tezduyar and T.~Kuraishi and H.~Hattori}, TITLE = {A Higher-Order {ST-VMS} Method for Turbocharger Analysis}, YEAR = {2015}, BOOKTITLE = {Proceedings of 13th Asian International Conference on Fluid Machinery}, ADDRESS = {Tokyo, Japan}, SERIES = {Paper No. AICFM13-153} }

[17]

H. Mochizuki, K. Takizawa, H. Hattori, T.E. Tezduyar, L. Pan, and S. Mei, “ST-VMS computational analysis of vertical-axis wind-turbine aerodynamics”, Proceedings of 13th Asian International Conference on Fluid Machinery (2015)
@INPROCEEDINGS{Mochizuki15a, AUTHOR = {H.~Mochizuki and K.~Takizawa and H.~Hattori and T. E.~Tezduyar and L.~Pan and S.~Mei}, TITLE = {{ST-VMS} Computational Analysis of Vertical-Axis Wind-Turbine Aerodynamics}, YEAR = {2015}, BOOKTITLE = {Proceedings of 13th Asian International Conference on Fluid Machinery}, ADDRESS = {Tokyo, Japan}, SERIES = {Paper No. AICFM13-150} }

[16]

T. Kuraishi, K. Takizawa, S. Tabata, S. Asada, and T.E. Tezduyar, “Multiscale thermo-fluid analysis of a tire”, Proceedings of the 19th Japan Society of Computational Engineering and Science Conference (2014)
@INPROCEEDINGS{Kuraishi14a, AUTHOR = {T.~Kuraishi and K.~Takizawa and S.~Tabata and S.~Asada and T. E.~Tezduyar}, TITLE = {Multiscale Thermo-Fluid Analysis of a Tire}, YEAR = {2014}, BOOKTITLE = {Proceedings of the 19th Japan Society of Computational Engineering and Science Conference}, ADDRESS = {Hiroshima, Japan} }

[15]

Y. Tsutsui, N. Toh, T. Terahara, K. Takizawa, T.E. Tezduyar, and C. Boswell, “Ringsail-parachute design studies based on aerodynamic-moment computation with resolved geometric porosity”, Proceedings of 58th Symposium on Space Science and Technology (2014)
@INPROCEEDINGS{Tsutsui14a, AUTHOR = {Y.~Tsutsui and N.~Toh and T.~Terahara and K.~Takizawa and T. E.~Tezduyar and C.~Boswell}, TITLE = {Ringsail-Parachute Design Studies Based on Aerodynamic-Moment Computation with Resolved Geometric Porosity}, YEAR = {2014}, BOOKTITLE = {Proceedings of 58th Symposium on Space Science and Technology}, ADDRESS = {Nagasaki, Japan} }

[14]

K. Takizawa, K. Schjodt, N. Kostov, A. Puntel, H. Takagi, and T.E. Tezduyar, “Patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent”, Proceedings of Annual Meeting of Japan Society of Mechanical Engineers (2012)
@INPROCEEDINGS{Takizawa12n, AUTHOR = {K.~Takizawa and K.~Schjodt and N.~Kostov and A.~Puntel and H.~Takagi and T. E.~Tezduyar}, TITLE = {Patient-Specific Computer Modeling of Blood Flow in Cerebral Arteries with Aneurysm and Stent}, YEAR = {2012}, BOOKTITLE = {Proceedings of Annual Meeting of Japan Society of Mechanical Engineers}, ADDRESS = {Kanazawa, Japan} }

[13]

T. Aoki, K. Sugihara, Y. Imai, and K. Takizawa, “High-accurate computation for compressible and incompressible fluid dynamics by multi-moment conservative scheme”, The 4th Japan-Taiwan Workshop on Mechanical and Aerospace Engineering (2007)
@INPROCEEDINGS{Aoki07b, AUTHOR = {T.~Aoki and K.~Sugihara and Y.~Imai and K.~Takizawa}, TITLE = {High-accurate Computation for Compressible and Incompressible Fluid Dynamics by Multi-moment Conservative Scheme}, YEAR = {2007}, BOOKTITLE = {The 4th Japan-Taiwan Workshop on Mechanical and Aerospace Engineering}, ADDRESS = {Japan} }

[12]

K. Sugihara, K. Takizawa, and T. Aoki, “Partly semi-Lagrangian Runge-Kutta time integration for IDO scheme”, 12th Japan Society for Computational Engineering and Science Conference (2007)
@INPROCEEDINGS{Sugihara07a, AUTHOR = {K.~Sugihara and K.~Takizawa and T.~Aoki}, TITLE = {Partly Semi-{L}agrangian {R}unge-{K}utta Time Integration for {IDO} Scheme}, YEAR = {2007}, BOOKTITLE = {12th Japan Society for Computational Engineering and Science Conference}, ADDRESS = {Tokyo, Japan} }

[11]

K. Takizawa and T. Aoki, “Conservative Interpolated Differential Operator (IDO) scheme”, 12th Japan Society for Computational Engineering and Science Conference (2007)
@INPROCEEDINGS{Takizawa07e, AUTHOR = {K.~Takizawa and T.~Aoki}, TITLE = {Conservative {I}nterpolated {D}ifferential {O}perator ({IDO}) Scheme}, YEAR = {2007}, BOOKTITLE = {12th Japan Society for Computational Engineering and Science Conference}, ADDRESS = {Tokyo, Japan} }

[10]

T. Aoki, Y. Imai, and K. Takizawa, “Conservative Interpolated Differential Operator (IDO) scheme”, Proceedings of International Conference on Recent Development of Numerical Schemes for Flow Problems (2007)
@INPROCEEDINGS{Aoki07a, AUTHOR = {T.~Aoki and Y.~Imai and K.~Takizawa}, TITLE = {Conservative {I}nterpolated {D}ifferential {O}perator ({IDO}) Scheme}, YEAR = {2007}, BOOKTITLE = {Proceedings of International Conference on Recent Development of Numerical Schemes for Flow Problems}, ADDRESS = {Fukuoka, Japan} }

[ 9]

K. Takizawa and T. Aoki, “Turbulent flow computations by conservative Interpolated Differential Operator (IDO) scheme”, Proceedings of International Conference on Recent Development of Numerical Schemes for Flow Problems (2007)
@INPROCEEDINGS{Takizawa07d, AUTHOR = {K.~Takizawa and T.~Aoki}, TITLE = {Turbulent Flow Computations by Conservative {I}nterpolated {D}ifferential {O}perator ({IDO}) Scheme}, YEAR = {2007}, BOOKTITLE = {Proceedings of International Conference on Recent Development of Numerical Schemes for Flow Problems}, ADDRESS = {Fukuoka, Japan} }

[ 8]

K. Takizawa and K. Tanizawa, “Computation of waves around a floating body by high accuracy CFD”, Conference Proceedings, The Japan Society of Naval Architects and Ocean Engineers (2006)
@INPROCEEDINGS{Takizawa06b, AUTHOR = {K.~Takizawa and K.~Tanizawa}, TITLE = {Computation of Waves around a Floating Body by High Accuracy {CFD}}, YEAR = {2006}, BOOKTITLE = {Conference Proceedings, The Japan Society of Naval Architects and Ocean Engineers}, ADDRESS = {Kobe, Japan} }

[ 7]

T. Nakamura, T. Ishikawa, T. Yabe, and K. Takizawa, “A new numerical solver for a 2-d non-linear-shallow water equation using a Soroban grid system”, Proceedings of Hydraulics Engineering, JSCE, 49 (2005) 685–690
@INPROCEEDINGS{Nakamura05a, AUTHOR = {T.~Nakamura and T.~Ishikawa and T.~Yabe and K.~Takizawa}, TITLE = {A New Numerical Solver for A 2-D Non-Linear-Shallow Water Equation using A {S}oroban Grid System}, VOLUME = {49}, YEAR = {2005}, BOOKTITLE = {Proceedings of Hydraulics Engineering, JSCE}, PAGES = {685–690} }

[ 6]

K. Takizawa, T. Yabe, and T.E. Tezduyar, “Flow calculations with the Soroban CIP scheme”, Proceedings of the Japan Society of Mechanical Engineers 17th Computational Mechanics Conference (2004)
@INPROCEEDINGS{Takizawa04a, AUTHOR = {K.~Takizawa and T.~Yabe and T. E.~Tezduyar}, TITLE = {Flow Calculations with the {S}oroban {CIP} Scheme}, YEAR = {2004}, BOOKTITLE = {Proceedings of the Japan Society of Mechanical Engineers 17th Computational Mechanics Conference}, ADDRESS = {Sendai, Japan} }

[ 5]

Y. Ogata, T. Yabe, K. Takizawa, and T. Ohkubo, “The analysis of electromagnetic waves using CIP scheme with Soroban grid”, Computational Fluid Dynamics 2004, 1 (2004) 141–146
@INPROCEEDINGS{Ogata04a, AUTHOR = {Y.~Ogata and T.~Yabe and K.~Takizawa and T.~Ohkubo}, TITLE = {The Analysis of Electromagnetic Waves Using {CIP} Scheme with {S}oroban Grid}, VOLUME = {1}, YEAR = {2004}, BOOKTITLE = {Computational Fluid Dynamics 2004}, PAGES = {141–146} }

[ 4]

M. Chino, K. Takizawa, and T. Yabe, “Experimental research on rotating skimmer”, Proceedings of FEDSM’03, 4th ASME–JSME Joint Fluids Engineering Conference (2003)
Times Cited in Scopus: 4
@INPROCEEDINGS{Chino03a, AUTHOR = {M.~Chino and K.~Takizawa and T.~Yabe}, TITLE = {Experimental research on rotating skimmer}, YEAR = {2003}, BOOKTITLE = {Proceedings of FEDSM'03, 4th ASME–JSME Joint Fluids Engineering Conference}, ADDRESS = {Hawai, USA} } Abstract:
This paper provides the experimental results on skimmer and gives some detailed information useful for benchmark test of computer codes that are now able to simulate the fluid-structure interaction. For this purpose, we specially designed the injection system that imposes reproducible rotational speed and injection speed on the skipper. The effect of rotation is discussed by changing rotation speed in a wide range.

[ 3]

K. Takizawa and T. Yabe, “Three-dimenisonal simulation of skimmer on water”, Proceedings of FEDSM’03, 4th ASME–JSME Joint Fluids Engineering Conference (2003)
@INPROCEEDINGS{Takizawa03a, AUTHOR = {K.~Takizawa and T.~Yabe}, TITLE = {Three-Dimenisonal Simulation of Skimmer on Water}, YEAR = {2003}, BOOKTITLE = {Proceedings of FEDSM'03, 4th ASME–JSME Joint Fluids Engineering Conference}, ADDRESS = {Hawai, USA} } Abstract:
The purpose of this paper is to develop a new three-dimensional hydrodynamic simulation algorithm for strongly-coupled fluid-structure interaction and demonstrate its ability to capture the complex surface of solid and liquid. For such an example, we use the skimmer phenomena with rotational motion. This result is compared with the experimental result given by Chino et.al. in this conference FEDSM2003-45171.

[ 2]

T. Yabe, F. Xiao, K. Takizawa, and K. Sakurai, “Three-phase flow calculation with conservative semi-Lagrangian CIP method”, ASME Joint U.S.–European Fluids Engineering Conference (2002)
@INPROCEEDINGS{Yabe02b, AUTHOR = {T.~Yabe and F.~Xiao and K.~Takizawa and K.~Sakurai}, TITLE = {Three-Phase Flow Calculation With Conservative Semi-{L}agrangian {CIP} Method}, YEAR = {2002}, BOOKTITLE = {ASME Joint U.S.–European Fluids Engineering Conference}, ADDRESS = {Montreal, Canada} } Abstract:
We present a review of the CIP method, which is a kind of semi-Lagrangian scheme and has been extended to treat incompressible flow in the framework of compressible fluid. Since it uses primitive Euler representation, it is suitable for multi-phase analysis. The recent version of this method guarantees the exact mass conservation even in the framework of semi-Lagrangian scheme. Comprehensive review is given for the strategy of the CIP method that has a compact support and sub-cell resolution including front capturing algorithm with functional transformation.

[ 1]

K. Takizawa and T. Yabe, “Development of multi dimensional conservative semi-Lagrangian scheme”, Proceedings of 14th Computational Fluid Dynamics, Japan Society of Fluid Mechanics (2000)
@INPROCEEDINGS{Takizawa00a, AUTHOR = {K.~Takizawa and T.~Yabe}, TITLE = {Development of Multi Dimensional Conservative Semi-{L}agrangian Scheme}, YEAR = {2000}, BOOKTITLE = {Proceedings of 14th Computational Fluid Dynamics, Japan Society of Fluid Mechanics}, ADDRESS = {Tokyo, Japan} }

Publications Summary:

1	Books
8	Edited Volumes
128	Journal Articles Indexed by the Web of Science
7	Other Journal Articles
27	Chapters in Books
42	Invited Conference Papers
20	Conference Papers