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Optical coherence tomography-based patient-specific coronary artery reconstruction and fluid-structure interaction simulation

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BIOMECHANICS AND MODELING IN MECHANOBIOLOGY 2020年第1期19卷 7-20页

作者： Wang, Jiaqiu Paritala, Phani Kumari Mendieta, Jessica Benitez Komori, Yo Raffel, Owen Christopher Gu, Yuantong Li, Zhiyong Queensland Univ Technol Sch Chem Phys & Mech Engn Brisbane Qld 4000 Australia Hokkaido Univ Deformat Control Lab Sapporo Hokkaido 0608628 Japan Prince Charles Hosp Dept Cardiol Brisbane Qld 4032 Australia Univ Queensland Sch Med Brisbane Qld 4072 Australia Southeast Univ Sch Biol Sci & Med Engn Nanjing 210096 Peoples R China

Plaque rupture is related to the mechanical stress it suffered. The value and distribution of the mechanical stress in plaque could help on assessing plaque vulnerability. To look into the stress conditions in the coronary artery, a patient-specific coronary model was created by using optical coherence tomography (OCT) and angiography imaging data. The reconstructed coronary model consisted of the structure of the lumen, the arterial wall and plaque components. Benefited by the high resolution of OCT, detailed structures such as the thin fibrous cap could be observed and built into the geometry. On this reconstructed coronary model, a fully coupled fluid-structure interaction (FSI) simulation was performed. The principle stress in coronary plaque and the wall shear stress (WSS) were analyzed. The FSI simulation results show that the cap thickness had a significant effect on the stress, and the principle stress at the thin cap area was more than double of those at the locations with a larger thickness. WSS is thought as an important parameter to assess the potentially dangerous areas of the atherosclerosis-prone (caused by low WSS) and the plaque rupture (high WSS). From the WSS plots of our FSI model, the area with abnormal WSS value was detected around the position where a lipid core existed. The FSI simulation results were compared with the results from the conventional structure-only and the computational fluid dynamics (CFD)-only computational models to quantify the difference between the three models. We found little difference in the principle stress results between the FSI and the structure-only model, but a significant difference between the FSI and the CFD-only model when looking into the WSS. The WSS values at the two observation spots from the CFD-only model were higher than the values from the FSI model by 17.95% and 22.66% in average, respectively. Furthermore, the FSI model detected more areas of low WSS, because the fluid domain could expand circumfer

关键词： Plaque rupture Optical coherence tomography Coronary reconstruction fluid-structure interaction

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A fluid-structure interaction analysis of anisotropic Dacron fabric used for aortic replacement

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JOURNAL OF fluidS AND structureS 2020年 97卷 103108-103108页

作者： Jayendiran, Raja Nour, Bakr Ruimi, Annie Texas A&M Univ Qatar Mech Engn Program Doha Qatar Weill Cornell Med Qatar Doha Qatar

We present the results of a computational study aimed at capturing the behavior over time of Dacron fabric used for surgical correction of aortic aneurysms. The study concerns the problem of compliance mismatch between the graft and the native aorta and is very important to clinicians. The aorta is represented by a sophisticated anisotropic hyperelastic model (GOH), which takes into account the orientation of the collagen fibers. The corrugations present on the Dacron fabric are modeled geometrically using experimental data retrieved from the literature. The viscoelastic behavior of the Dacron graft reported by clinicians is also taken into account. Mechanical quantities experienced by the graft sewn to an aortic segment are obtained using fluid-structure interaction (FSI) simulations assuming realistic blood flow conditions. Both ascending and descending aorta with two curvatures are considered. Results of this study indicate that (i) the strains on the Dacron-aorta structure increase with increasing curvature and over time (ii) the simulations are capable of capturing stress concentrations at the junction of the graft and the aorta and (iii) the wall shear stresses (WSS) are substantially higher on the aortic segment than on the Dacron graft. (c) 2020 Elsevier Ltd. All rights reserved.

关键词： Human aorta Dacron graft fluid-structure interaction Anisotropic hyperelastic Viscoelastic

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An immersed boundary-lattice Boltzmann method for fluid-structure interaction problems involving viscoelastic fluids and complex geometries

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JOURNAL OF COMPUTATIONAL PHYSICS 2020年 415卷 109487-109487页

作者： Ma, Jingtao Wang, Zhen Young, John Lai, Joseph C. S. Sui, Yi Tian, Fang-Bao Univ New South Wales Sch Engn & Informat Technol Canberra ACT 2600 Australia Queen Mary Univ London Sch Engn & Mat Sci London E1 4NS England

An immersed boundary-lattice Boltzmann method (IB-LBM) for fluid-structure interaction (FSI) problems involving viscoelastic fluids and complex geometries is presented in this paper. In this method, the fluid dynamics and the constitutive equations of viscoelastic fluids are both solved using the lattice Boltzmann method. In order to enhance numerical stability in solving the constitutive equations, an artificial damping is introduced which does not affect the numerical results if the damping effect is much smaller than the relaxation and the convective effects. The structural dynamics including 2D and 3D capsules, 2D and 3D rigid particles and flags, are solved by the finite difference method (2D capsules, 2D and 3D rigid particles and flags) and the finite element method (3D capsules). The interaction between the solid structure and the fluid is enforced by an immersed boundary method. The overall framework of this method is very simple, enabling modelling FSI problems involving viscoelastic fluids and the inertia of both fluids and structures. It is very efficient for FSI problems involving high Weissenberg numbers flows, large deformations and complicated geometries without any preconditioner. This work uses IB-LBM to solve for the first time, flows involving viscoelastic fluids coupled with non-massless deforming structures. The method is also capable of solving very high Weissenberg number problems, as demonstrated by simulations of flexible particle flows at Wi = 100. The present method and models are validated by several cases including a 2D rigid particle migration in a Giesekus Couette flow, a spherical particle rotation in an Oldroyd-B shear flow, a spherical particle settling in a FENE-CR fluid, 2D and 3D capsules deformation in a Newtonian shear flow, and a 3D flag flapping in a Newtonian free stream. In addition, the present method is also applied to simulate the deformation of 2D and 3D capsules in an Oldroyd-B shear flow, a 3D flag flapping in an Old

关键词： Immersed-boundary method Lattice Boltzmann method fluid-structure interaction Viscoelastic fluids

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fluid-structure interaction between pulsatile blood flow and a curved stented coronary artery on a beating heart: A four stent computational study

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COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2019年第Jun.15期350卷 679-700页

作者： Bukac, Martina Canic, Suncica Tambaca, Josip Wang, Yifan Univ Notre Dame Dept Appl & Computat Math & Stat Notre Dame IN 46556 USA Univ Calif Berkeley Dept Math Berkeley CA 94720 USA Univ Zagreb Dept Math Zagreb Croatia

This work focuses on fluid-structure interaction (FSI) between a curved (tortuous) coronary artery with an implanted stent, pulsatile blood flow, and heart contractions. The goal is to understand which geometric distribution of stent struts, given by four different, commercially available stent geometries, is least likely to be associated with parameters correlated with pathobiologic responses leading to restenosis, in the case of curved coronary arteries, whose curvature changes significantly with each heart contraction. The stent geometries considered in this study correspond to a Palmaz-like stent, an Express-like stent, a Cypher-like stent, and a Xience-like stent. The biomechanical environment induced by each implanted stent is evaluated in terms of displacement magnitude, Von Mises stress, normal stress experienced by the intimal layer with implanted stent, and wall shear stress. Arterial walls are modeled as multi-layered structures: the intimal layer with the internal elastic laminae is modeled as a nonlinearly elastic membrane, while the media-adventitia complex is modeled as a 3D linearly elastic material. The Navier-Stokes equations for an incompressible, viscous fluid, are used to model the blood flow. Full, two-way coupling between the fluid and the structure, and between the thin and thick structure, is considered. To include the effects of the force exerted by the pericardium and heart muscle contractions, external force is applied to the coronary artery walls. Pulsatile boundary conditions were imposed at the inlet and outlet of the coronary segment, approximating measured diastolic coronary flow. The presence of an implanted stent was modeled by its impact on the mass and elasticity properties of the intimal layer where the stent is located. The stent material is modeled as a 316L stainless steel. A novel, loosely coupled partitioned scheme combined with an ALE approach was used to solve this nonlinear FSI problem. It was found that the Cypher-like

关键词： fluid-structure interaction Curved coronary artery Coronary stent Loosely coupled partitioned scheme Arbitrary Lagrangian-Eulerian formulation

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An explicit MPS/FEM coupling algorithm for three-dimensional fluid-structure interaction analysis

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ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS 2020年 121卷 192-206页

作者： Zheng, Zumei Duan, Guangtao Mitsume, Naoto Chen, Shunhua Yoshimura, Shinobu Univ Tokyo Dept Syst Innovat Bunkyo Ku Hongo 7-3-1 Tokyo 1138656 Japan Univ Tokyo Dept Nucl Engn & Management Bunkyo Ku Hongo 7-3-1 Tokyo 1138656 Japan Univ Tsukuba Fac Engn Informat & Syst Tennodai 1-1-1 Tsukuba Ibaraki 3058573 Japan

Currently, accurate simulations of fluid structure interaction (FSI) problems still remain a challenging task in the academic community. The purpose of this work is to develop a three-dimensional (3D) coupling algorithm to achieve the end, where the explicit moving particle simulation method (MPS) and the finite element method (FEM) are respectively employed to account for fluid flows and structural deformation. The developed coupling algorithm inherits the advantages of the aforementioned methods, while also addressing their shortcomings. We start by extending a newly proposed ghost cell boundary (GCB) model, which has proved to be an effective method to deal with the wall boundary of complicated shapes, to three dimensions. For the problems of interest, the finite elements for structural discretization serve as ghost cells for interaction force calculation, thereby providing an easy and natural way for the construction of ghost cells. The interactions between fluids and structures are dealt with using an integral version of the MPS model, and the resultant interaction forces calculated at integration points of a cell are distributed to finite element nodes for the update of nodal kinematics in the context of an explicit time integration scheme. The effectiveness and accuracy of the 3D GCB model are validated via two numerical examples, i.e., the dam break test and the water flow in a rotating gear test. Afterwards, the developed coupling algorithm is applied to two common FSI problems, i.e., the dam break tests with respective an elastic obstacle and an elastic gate. The good agreements between our simulation results and the existing data in literature demonstrate the accuracy and capacity of the developed coupling algorithm in solving FSI problems.

关键词： MPS-FEM coupling fluid-structure interaction Ghost cell boundary model Gauss integration

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A time-dependent FEM-BEM coupling method for fluid-structure interaction in 3d

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APPLIED NUMERICAL MATHEMATICS 2020年 152卷 49-65页

作者： Gimperlein, Heiko Oezdemir, Ceyhun Stephan, Ernst P. Heriot Watt Univ Maxwell Inst Math Sci Edinburgh EH14 4AS Midlothian Scotland Heriot Watt Univ Dept Math Edinburgh EH14 4AS Midlothian Scotland Univ Paderborn Inst Math Warburger Str 100 D-33098 Paderborn Germany Leibniz Univ Hannover Inst Appl Math D-30167 Hannover Germany Graz Univ Technol Inst Mech A-8010 Graz Austria

We consider the well-posedness and a priori error estimates of a 3d FEM-BEM coupling method for fluid-structure interaction in the time domain. For an elastic body immersed in a fluid, the exterior linear wave equation for the fluid is reduced to an integral equation on the boundary involving the Poincare-Steklov operator. The resulting problem is solved using a Galerkin boundary element method in the time domain, coupled to a finite element method for the Lame equation inside the elastic body. Based on ideas from the time independent coupling formulation, we obtain an a priori error estimate and discuss the implementation of the proposed method. Numerical experiments illustrate the performance of our scheme for model problems. (C) 2020 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： fluid-structure interaction FEM-BEM coupling Space-time methods A priori error estimate Wave equation

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A class of analytic solutions for verification and convergence analysis of linear and nonlinear fluid-structure interaction algorithms

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COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2020年第0期362卷 112841-000页

作者： Hessenthaler, Andreas Balmus, Maximilian Roehrle, Oliver Nordsletten, David Univ Stuttgart Inst Modelling & Simulat Biomech Syst Pfaffenwaldring 5a D-70569 Stuttgart Germany Kings Coll London St Thomas Hosp Sch Biomed Engn & Imaging Sci 4th FL Rayne Inst London SE1 7EH England Univ Michigan Dept Biomed Engn & Cardiac Surg NCRC B202800 Plymouth Rd Ann Arbor MI 48109 USA

fluid-structure interaction (FSI) problems are pervasive in the computational engineering community. The need to address challenging FSI problems has led to the development of a broad range of numerical methods addressing a variety of application-specific demands. While a range of numerical and experimental benchmarks are present in the literature, few solutions are available that enable both verification and spatiotemporal convergence analysis. In this paper, we introduce a class of analytic solutions to FSI problems involving shear in channels and pipes. Comprised of 16 separate analytic solutions, our approach is permuted to enable progressive verification and analysis of FSI methods and implementations, in two and three dimensions, for static and transient scenarios as well as for linear and hyperelastic solid materials. Results are shown for a range of analytic models exhibiting progressively complex behavior. The utility of these solutions for analysis of convergence behavior is further demonstrated using a previously published monolithic FSI technique. The resulting class of analytic solutions addresses a core challenge in the development of novel FSI algorithms and implementations, providing a progressive testbed for verification and detailed convergence analysis. (C) 2020 ElsevierB.V. All rights reserved.

关键词： fluid-structure interaction Analytic solutions Convergence analysis Navier-Stokes equations Linear elasticity Hyperelasticity

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Propulsion performance investigation of bio-inspired nano rotor base on fluid-structure interaction

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INTERNATIONAL JOURNAL OF MICRO AIR VEHICLES 2020年第12期12卷 -页

作者： Zhao, Shanyong Liu, Zhen Che, Penglei Li, Bingfei Dang, Tianjiao Bu, Chen Xi An Jiao Tong Univ Sch Aerosp State Key Lab Strength & Vibrat Mech Struct Xian Shaanxi Peoples R China

In this paper, the bio-inspired blade motion is introduced to improve the propulsive performance of nano rotor at an ultra-low Reynolds number. However, the complex flow interacts with the flexible composite blade structure resulting in the change of nano rotor propulsion performance and the vibration of blade structure. A composite nano rotor with blade-pitch motion is investigated computationally with a computational solvers based on fluid-structure interaction. The finite element model for the composite rotor is created and verified with a non-contact modal test. It is found that the simulation results matched well with the experimental results. Successively, the propulsive performance of a rigid nano rotor is studied. The propulsive performance of the nano rotor is analysed at different bio-inspired pitch frequencies. The results show that the figure of merit of the bio-inspired pitch rotor increases because of the bio-inspired blade pitch motion. And it is also found that the improvement of the propulsive performance of the nano rotor varies with the pitch frequency. The propulsive performance of the flexible bio-inspired nano rotor is also studied with by using fluid-structure interaction method. It is found that the computational results for flexible nano rotor are lower than that for rigid nano rotor. It is evident that it is necessary to consider the flexibility of the composite nano rotor when investigating the propulsion performance of bio-inspired nano rotor. And the response of blade structure is also studied. Structural dynamic analysis shows that the blade structure vibrates with small amplitude. And two peak values are found at the rotation frequency and the fundamental frequency of the nano rotor structure.

关键词： Bio-inspired nano rotor flexible blade fluid-structure interaction propulsion performance low Reynolds number

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A scalable framework for the partitioned solution of fluid-structure interaction problems

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COMPUTATIONAL MECHANICS 2020年第2期66卷 471-489页

作者： Naseri, Alireza Totounferoush, Amin Gonzalez, Ignacio Mehl, Miriam David Perez-Segarra, Carlos Univ Politecn Cataluna BarcelonaTech UPC ESEIAAT Heat & Mass Transfer Technol Ctr CTTC C Colom 11 Barcelona 08222 Spain Univ Stuttgart Inst Parallel & Distributed Syst IPVS Univ Str 38 D-70569 Stuttgart Germany

In this work, we present a scalable and efficient parallel solver for the partitioned solution of fluid-structure interaction problems through multi-code coupling. Two instances of an in-house parallel software, Termofluids, are used to solve the fluid and the structural sub-problems, coupled together on the interface via the preCICE coupling library. For fluid flow, the Arbitrary Lagrangian-Eulerian form of the Navier-Stokes equations is solved on an unstructured conforming grid using a second-order finite-volume discretization. A parallel dynamic mesh method for unstructured meshes is used to track the moving boundary. For the structural problem, the nonlinear elastodynamics equations are solved on an unstructured grid using a second-order finite-volume method. A semi-implicit FSI coupling method is used which segregates the fluid pressure term and couples it strongly to the structure, while the remaining fluid terms and the geometrical nonlinearities are only loosely coupled. A robust and advanced multi-vector quasi-Newton method is used for the coupling iterations between the solvers. Both the fluid and the structural solver use distributed-memory parallelism. The intra-solver communication required for data update in the solution process is carried out using non-blocking point-to-point communicators. The inter-code communication is fully parallel and point-to-point, avoiding any central communication unit. Inside each single-physics solver, the load is balanced by dividing the computational domain into fairly equal blocks for each process. Additionally, a load balancing model is used at the inter-code level to minimize the overall idle time of the processes. Two practical test cases in the context of hemodynamics are studied, demonstrating the accuracy and computational efficiency of the coupled solver. Strong scalability test results show a parallel efficiency of 83% on 10,080 CPU cores.

关键词： fluid-structure interaction Partitioned method Multi-code coupling Scalability High performance computing

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Developing the Actuator Disk Model to Predict the fluid-structure interaction in Numerical Simulation of Multimegawatt Wind Turbine Blades

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JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME 2020年第3期142卷 031204页

作者： Behrouzifar, Ali Darbandi, Masoud Sharif Univ Technol Ctr Excellence Aerosp Syst Dept Aerosp Engn Tehran Iran

The fluid-structure interaction (FSI) is generally addressed in multimegawatt wind turbine calculations. From the fluid flow perspective, the semi-analytical approaches, like actuator disk (AD) model, were commonly used in wind turbine rotor calculations. Indeed, the AD model can effectively reduce the computational cost of full-scale numerical methods. Additionally, it can substantially improve the results of pure analytical methods. Despite its great advantages, the AD model has not been developed to simulate the FSI problem in wind turbine simulations. This study first examines the effect of constant (rigid) cone angle on the performance of the chosen benchmark wind turbine. As a major contribution, this work subsequently extends the rigid AD model to nonrigid applications to suitably simulate the FSI. The new developed AD-FSI solver uses the finite-volume method to calculate the aerodynamic loads and the beam theory to predict the structural behaviors. A benchmark megawatt wind turbine is simulated to examine the accuracy of the newly developed AD-FSI solver. Next, the results of this solver are compared with the results of other researchers, who applied various analytical and numerical methods to obtain their results. The comparisons indicate that the new developed solver calculates the aerodynamic loads reliably and predicts the blade deflection very accurately.

关键词： actuator disk model wind turbine flexible blade fluid-structure interaction blade element momentum theory numerical study renewable energy

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