Date of Award

Fall 2004

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

Ayodeji Demuren

Committee Member

Arthur C. Taylor III

Committee Member

Sebastian Bawab

Call Number for Print

Special Collections; LD4331.E56 D53 2004

Abstract

A three-dimensional computational fluid dynamics study of blood flow through stenotic arteries has been conducted. Flow phenomena, such as separation regions and turbulence, can be found distal to an arterial stenosis. Frequently, a bypass graft using an end-to-side technique is attached to a stenotic artery to restore adequate blood flow. However, a significant percentage of these grafts fail after thirty postoperative days due to intimal hyperplasia development around the distal anastomosis. Moreover, aberrant wall shear rates have been implicated as a factor in the development of intimal hyperplasia. Thus, the present study examines whether placement of the distal end of a bypass graft anastomosis in the post-stenotic region of blood flow influences shear rates around the distal anastomosis, thereby establishing the possibility of an optimal distal placement that extends patent blood flow achieved by the bypass operation. Therefore, different graft attachment locations were studied using a 51 % and a 75% stenotic arterial model. Steady, incompressible, Newtonian flow was assumed and simulated on a locally structured multi-block mesh with hexahedral elements. Furthermore, a finite-volume method and a pressure correction scheme, SIMPLE, were used in addition to implicit Gauss-Siedel iteration to solve the full Navier-Stokes equations and turbulent kinetic energy and specific dissipation rate equations with second-order accuracy. A preliminary study was conducted and confirmed acceptable prediction accuracy of the present computational code and technique. Consequently, the highest shear rates were recorded around the bypass graft anastomosis placed farthest downstream from the stenosis for both 51% and 75% stenotic models. Moreover, the lowest inner wall shear rates were recorded around the distal bypass graft anastomosis of the 51 % stenotic model placed in a separation region, and the lowest outer wall shear rates were recorded around the distal bypass graft anastomosis of the 75% stenotic model placed in the reattachment region of separated flow. This indicates that distal placement of an end-to-side bypass graft anastomosis influences shear rates around the distal anastomosis, and with further study, an optimal placement could be determined that possibly extends patent blood flow to afflicted tissues.

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DOI

10.25777/brbc-ep76

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