A flow-wall coupled model is developed by externally coupling of the CFD (Computational Fluid Dynamics) package FLUENT and the FEM (Finite Element Method) package ABAQUS using a MATLAB script. This model is used to study the flow and stress field for idealised stenosed arteries. The impedance of the stenosis is estimated by an LCR model and the boundary conditions are derived from a 1D transmission line model. Studies on localized stiffness for straight and mild stenosed arteries showed that the localized stiffness has a negligible effect on the pressure, local velocity magnitude and was wall shear stress (WSS) field, but it has a significant effect on the wall motion around the diseased part. Simulations of the blood flow and wall motion (WM) for different degrees of stenosis under physiologically realistic conditions was carried out. The results showed that maximum WSS increases substantially with the increase of stenosis severity. The maximum WSS is about 10Pa for healthy arteries, it reaches 45pa for a 30% stenosis (by diameter), at which endothelial stripping may occur, and for >=50% stenoses, the maximum WSS values were greater than 100Pa. Wall motion was increasingly constrained as the degree of stenosis increased. It was constrained at the throat by 55% for the 30% stenosis, 86% for the 50% stenosis; while for the 70% stenosis, WM at the throat is negligible through the whole cycle. With the increase of the degrees of stenosis, the maximum circumferential stress varies within 20%, which is a small variation compare with the changes in WSS as the degree of stenosis increases. However, the localized stiffness and physiological axial stretch has substantial influence on the circumferential stress distributions. Maximum circumferential stress was found at the shoulders of plaques with the presence of localized stiffness and physiological axial stretch.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:657839 |
| Date | January 2006 |
| Creators | Li, Mingxiu |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/12415 |
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