scholarly journals Quantifying Effect of Intraplaque Hemorrhage on Critical Plaque Wall Stress in Human Atherosclerotic Plaques Using Three-Dimensional Fluid-Structure Interaction Models

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Xueying Huang ◽  
Chun Yang ◽  
Gador Canton ◽  
Marina Ferguson ◽  
Chun Yuan ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Large Scale ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Wall Stress ◽  
Intraplaque Hemorrhage ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Volume Curve ◽  
The Impact

Recent magnetic resonance studies have indicated that intraplaque hemorrhage (IPH) may accelerate plaque progression and play an important role in plaque destabilization. However, the impact of hemorrhage on critical plaque wall stress (CPWS) and strain (CPWSn) has yet to be determined. The objective of this study was to assess the effect of the presence and size of IPH on wall mechanics. The magnetic resonance image (MRI) of one patient with histology-confirmed IPH was used to build eight 3D fluid-structure interaction (FSI) models by altering the dimensions of the existing IPH. As a secondary end point, the combined effect of IPH and fibrous cap thickness (FCT) was assessed. A volume curve fitting method (VCFM) was applied to generate a mesh that would guarantee numerical convergence. Plaque wall stress (PWS), strain (PWSn), and flow shear stress (FSS) were extracted from all nodal points on the lumen surface for analysis. Keeping other conditions unchanged, the presence of intraplaque hemorrhage caused a significant increase (27.5%) in CPWS; reduced FCT caused an increase of 22.6% of CPWS. Similar results were found for CPWSn. Furthermore, combination of IPH presence, reduced FCT, and increased IPH volume caused an 85% and 75% increase in CPWS and CPWSn, respectively. These results show that intraplaque hemorrhage has considerable impact on plaque stress and strain conditions and accurate quantification of IPH could lead to more accurate assessment of plaque vulnerability. Large-scale studies are needed to further validate our findings.

The Simulation of Dual Layer Fuel Tank During the Impact With the Ground Based on Parallel Computing

2007 ◽  
Vol 2 (4) ◽  
pp. 366-373 ◽  
Author(s):  
Li Zheng ◽  
Jin Xiang-long ◽  
Chen Xiang-dong
Keyword(s):  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Fuel Tank ◽  
Woven Fabric ◽  
Structural Domain ◽  
Arbitrary Lagrangian Eulerian ◽  
Fluid Structure ◽  
Bisection Algorithm ◽  
Structure Interaction ◽  
The Impact

The crashworthiness of a dual layer fuel tank, with the outer layer made of metal and the inner layer made of woven fabric composite material, is fundamental for the survivability of an impact with the ground in emergency. In this research, the simulation of a three-dimensional dual layer fuel tank in the impact with the ground is achieved through the multimaterial arbitrary Lagrangian-Eulerian (ALE) finite element method because of its ability to control mesh geometry independently of geometry. At the same time, the naked flexible tank in the impact with the ground is simulated for the evaluation of the outer metal tank. The ALE description is adopted for the fluid domain, while for the structural domain the Lagrangian formulation is considered. The computation of the fluid-structure interaction and the impact contact between the tank and the ground are realized by the penalty-based coupling method. Then, the dynamic behaviors of the dual layer fuel tank and the naked flexible tank in the impact are analyzed. In the meantime, the parallelism of the dual layer fuel tank is discussed because the computation of the fluid-structure interaction and the impact contact is quite time consuming. Based on domain decomposition, the recursive coordinate bisection (RCB) is improved according to the time-consuming characteristics of fluid-filled tank in the impact. The result indicates, comparing with the RCB algorithm, that the improved recursive coordinate bisection algorithm has improved the speedup and parallel efficiency.

Verification of a Total Lagrangian ANCF Solution Procedure for Fluid–Structure Interaction Problems

2017 ◽  
Vol 2 (4) ◽  
Author(s):  
Emanuele Grossi ◽  
Ahmed A. Shabana
Keyword(s):  
Finite Element ◽  
Fluid Model ◽  
Mass Matrix ◽  
Fluid Structure Interaction ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Position Vector ◽  
Fluid Structure ◽  
Structure Interaction ◽  
The Impact

The objective of this investigation is to verify a new total Lagrangian continuum-based fluid model that can be used to solve two- and three-dimensional fluid–structure interaction problems. Large rotations and deformations experienced by the fluid can be captured effectively using the finite element (FE) absolute nodal coordinate formulation (ANCF). ANCF elements can describe arbitrarily complex fluid shapes without imposing any restriction on the amount of rotation and deformation within the finite element, ensure continuity of the time-rate of position vector gradients at the nodal points, and lead to a constant mass matrix regardless of the magnitude of the fluid displacement. Fluid inertia forces are computed, considering the change in the fluid geometry as the result of the large displacements. In order to verify the ANCF solution, the dam-break benchmark problem is solved in the two- and three-dimensional cases. The motion of the fluid free surface is recorded before and after the impact on a vertical wall placed at the end of the dam dry deck. The results are in good agreement with those obtained by other numerical methods. The results obtained in this investigation show that the number of degrees-of-freedom (DOF) required for ANCF convergence is around one order of magnitude less than what is required by other existing methods. Limitations and advantages of the verified ANCF fluid model are discussed.

Modeling of aortic valve stenosis using fluid-structure interaction method

Perfusion ◽  
2021 ◽  
pp. 026765912199854
Author(s):  
Mohammad Javad Ghasemi Pour ◽  
Kamran Hassani ◽  
Morteza Khayat ◽  
Shahram Etemadi Haghighi
Keyword(s):  
Blood Flow ◽  
Aortic Valve ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Relaxation Phase ◽  
Exercise Condition ◽  
Time Dependent Domain ◽  
Comparison Of The Results

Background and objectives: Fluid structure interaction (FSI) is defined as interaction of the structures with contacting fluids. The aortic valve experiences the interaction with blood flow in systolic phase. In this study, we have tried to predict the hemodynamics of blood flow through a normal and stenotic aortic valve in two relaxation and exercise conditions using a three-dimensional FSI method. Methods: The aorta valve was modeled as a three-dimensional geometry including a normal model and two others with 25% and 50% stenosis. The geometry of the aortic valve was extracted from CT images and the models were generated by MMIMCS software and then they were implemented in ANSYS software. The pulsatile flow rate was used for all cases and the numerical simulations were conducted based on a time-dependent domain. Results: The obtained results including the velocity, pressure, and shear stress contours in different systolic time sequences were explained and discussed. The maximum blood flow velocity in relaxation phase was obtained 1.62 m/s (normal valve), 3.78 m/s (25% stenosed valve), and 4.73 m/s (50% stenosed valve). In exercise condition, the maximum velocities are 2.86, 4.32, and 5.42 m/s respectively. The maximum blood pressure in relaxation phase was calculated 111.45 mmHg (normal), 148.66 mmHg (25% stenosed), and 164.21 mmHg (50% stenosed). However, the calculated values in exercise situation were 129.57, 163.58, and 191.26 mmHg. The validation of the predicted results was also conducted using existing literature. Conclusions: We believe that such model are useful tools for biomechanical experts. The further studies should be done using experimental data and the data are implemented on the boundary conditions for better comparison of the results.

Scalability study of an implicit solver for coupled fluid-structure interaction problems on unstructured meshes in 3D

2016 ◽  
Vol 32 (2) ◽  
pp. 207-219 ◽  
Author(s):  
Fande Kong ◽  
Xiao-Chuan Cai
Keyword(s):  
Stokes Equations ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Coupled System ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Krylov Method ◽  
Fine Mesh ◽  
Processor Cores ◽  
Fully Coupled

Fluid-structure interaction (FSI) problems are computationally very challenging. In this paper we consider the monolithic approach for solving the fully coupled FSI problem. Most existing techniques, such as multigrid methods, do not work well for the coupled system since the system consists of elliptic, parabolic and hyperbolic components all together. Other approaches based on direct solvers do not scale to large numbers of processors. In this paper, we introduce a multilevel unstructured mesh Schwarz preconditioned Newton–Krylov method for the implicitly discretized, fully coupled system of partial differential equations consisting of incompressible Navier–Stokes equations for the fluid flows and the linear elasticity equation for the structure. Several meshes are required to make the solution algorithm scalable. This includes a fine mesh to guarantee the solution accuracy, and a few isogeometric coarse meshes to speed up the convergence. Special attention is paid when constructing and partitioning the preconditioning meshes so that the communication cost is minimized when the number of processor cores is large. We show numerically that the proposed algorithm is highly scalable in terms of the number of iterations and the total compute time on a supercomputer with more than 10,000 processor cores for monolithically coupled three-dimensional FSI problems with hundreds of millions of unknowns.

Analysis of a Nonlinear Friction Damping Mechanism in a Fluid-Structure Interaction System

1995 ◽  
Author(s):  
Oded Gottlieb ◽  
Michael Feldman ◽  
Solomon C. S. Yim
Keyword(s):  
Large Scale ◽  
Fluid Structure Interaction ◽  
Simulated Data ◽  
Identification Algorithm ◽  
Nonlinear Friction ◽  
Friction Damping ◽  
Restoring Force ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Interaction System

Abstract Analysis of a nonlinear friction damping mechanism in a fluid-structure interaction system is performed by combining a generalized averaging procedure with a recently developed identification algorithm based on the Hilbert transform. The system considered includes a nonlinear restoring force and a nonlinear dissipation force incorporating both viscous and structural damping. Frequency and damping response backbone curves obtained from simulated data are compared with analytical and approximate solutions and are found to be accurate. An example large scale experiment exhibiting viscous and Coulomb damping is also analyzed resulting in identification of system parameters.

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