THESIS
2016
xi, 73 pages : illustrations (some color) ; 30 cm
Abstract
Atherosclerosis is a common and hazardous cardiovascular pathology that affects many humans
each year. Experimental and computational studies have implicated a relationship with the local
hemodynamics, such as wall shear stress (WSS), caused by blood flow in the vessels.
Specifically, studies link the hemodynamics to a morphological response by the shear-sensitive
endothelial cells (ECs) that line the vessel and the biological processes they regulate. However,
blood transport computational simulation studies in the past assume a smooth wall and do not
account for the shear-dependent shape of ECs when analyzing shear stress and other
hemodynamics. In order to evaluate the effects of EC morphology on shear stress, a preliminary
study was done by creating 3D models of straight and...[
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Atherosclerosis is a common and hazardous cardiovascular pathology that affects many humans
each year. Experimental and computational studies have implicated a relationship with the local
hemodynamics, such as wall shear stress (WSS), caused by blood flow in the vessels.
Specifically, studies link the hemodynamics to a morphological response by the shear-sensitive
endothelial cells (ECs) that line the vessel and the biological processes they regulate. However,
blood transport computational simulation studies in the past assume a smooth wall and do not
account for the shear-dependent shape of ECs when analyzing shear stress and other
hemodynamics. In order to evaluate the effects of EC morphology on shear stress, a preliminary
study was done by creating 3D models of straight and curved vessels with either no cells,
sheared ECs, or unsheared ECs. A kernal independent fast multipole boundary element method
(BEM) code was used to simulate Stokes flow. This initial study on smaller vessels with a
regular, idealized EC surface found that in all cases, maximum WSS was increased and average
WSS was decreased with the inclusion of ECs. This idea was then applied to patient-specific,
realistic, aorta models which are commonly used in atherosclerosis studies. A multiscale
algorithm which applies a wall velocity boundary condition representing blood flow over an EC
(slip velocity) in a finite volume method (FVM) simulation of aortic blood flow was developed.
Simulation results from a branchless aortic aneurysm model with revealed that the inclusion of
EC wall geometry in pathologically disturbed flow resulted in an increase in vessel wall area
with low time-averaged WSS and high OSI, as well as large changes in time-dependent WSS at
various points of the vessel. These results show that EC morphology should be considered in
future studies using CFD to identify pathology triggering hemodynamic parameters.
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