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Numerical Fluid–Structure Interaction and non-Newtonian Simulation of Blood Flow in a Compliant Carotid Bifurcation

Toloui, Mostafa | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40583 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firoozabadi, Bahar; Saidi, Mohammad Saeid
  7. Abstract:
  8. Researchers have done a lot of studies about the use of CFS in blood flow modeling in order to improve the supplementary devices or find mechanical factors which cause artery to be diseased. Blood is a complex rheological fluid, blood flow is a pulastile flow, and blood flow field interacts with the deformable vessel wall. Thus, blood flow modeling like other biological phenomena has its own complexities such as anisotropy, vsicoelasticity, and nonlinearity in stress-strain relationship of vessel wall. To explore the role of hemodynamics in the initiation and progression of stenosis in carotid artery bifurcation, a 3D Computational Fluid Dynamics (CFD) technique is applied. The effect of four rheology models (i.e., Newtonian, power law, Quemada, and Carreau-Yasuda) is investigated in an ideal geometry and a healthy patient specific geometry which is extracted from in-vivo data. In addition to different hemodynamics, various mechanical phenomena are considered as the causes of atherosclerosis. In this study, the finite element method (FEM) was applied to simulate the physiologic circumferential strain/stress in the carotid bifurcation by the use of CFD modeling results as the boundary conditions. Meanwhile, to investigate the effect of vessel wall flexibility on distribution hemodynamics, a fully-coupled fluid–structure interaction (FSI) analysis was applied for various constitutive equations of blood viscosity (Newtonian, Carreau-Yasuda). The pulsatile boundary conditions based on a physiological flow velocity waveform and investigate the relationship between the hemodynamic forces and vascular morphology for an idealized carotid artery was used. The results show that the interaction between the blood flow and arterial deformation alters the hemodynamic forces acting on the arterial wall and the interaction strongly depends on the values of elasticity. In other words, stiffening of the carotid wall led to significant decrease in mean value of flow rate and wall shear stress distribution.Based on our simulations, deformablity of vessel wall doesn’t have a dominant effect on the flow field at last two phase of cariac cycle, though FSI modeling revealed that the shear-thinning rheological model plays a key role at these two phase as steady simulations. Further, it can be seen that the highest elevated strain level are seen in the vicinity of apex
  9. Keywords:
  10. Computational Fluid Dynamics (CFD) ; Fluid-Structure Interaction ; Non-Newtonian Flow ; Newtonian Fluid Flow ; Pulse Current ; Carotid Bifurcation ; Wall Shear Stress (WSS) ; Nondivider Wall ; Wall Strain

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