Copyright © 2012 American Scientific Publishers All rights reserved Printed in the United States of America RESEARCH ARTICLE Advanced Science Letters Vol. 5, 1–9, 2011 Numerical Investigation of Non-Newtonian Pulsatile Blood Flow in Atherosclerotic Coronary Artery S. Ghaffari ∗ , A. Saeedmanesh, and M. S. Karimi Mechanical Engineering Department, University College of Engineering, University of Tehran, Tehran, Iran In the present work, flow characteristics of non-Newtonian blood flow in the atherosclerotic Right Coronary Artery are investigated by numerical methods. The rheology of the flowing blood is modeled by a generalized Power law model. Plaque deposits can rupture and break away, traveling downstream to lodge in a smaller artery and block blood flow to the different parts of the body. A mathematical modeling is applied to analyze the pulsatile blood flow. Transient Navier-Stokes equations in 2D idealized arterial model of a bending artery are discretized using the finite volume method and solved by SIMPLE algorithm in curvilinear coordinate to investigate influence of blood viscosity on plaque’s wall shear stress. Shear stress plays an important role in the rupture of the plaque. The amount of wall shear stress on the surface of atherosclerotic plaque is obtained for various times, and different Power law indices (n). It is observed that how blood dilution modifies the flow patterns and decreases the destructive effects of Atherosclerotic plaque. Keywords: Atherosclerotic Artery, Non-Newtonian Fluid, Curvilinear Coordinate, Pulsatile Flow. 1. INTRODUCTION Atherosclerosis which is a major underlying cause of angina and myocardial infarction mentions progressive disease of the arteries described by partial thickening of the inner lining of the arte- rial walls. Such a disease caused by athermanous plaques which are made of cholesterol, waste products from the cells, calcium, lipid core and a fibro-muscular a cap. The molecular viscosity disturbances, the local velocity and the geometrical pattern of the artery are the other factors that may gradually cause to the creation of cardiac plaques. 1 2 A typical occurrence which com- monly happens is that because of the flow separation and creation of secondary and recirculation flows, plaques can be usually seen in segments of arteries. 3–6 The artery’s diameter is changed, and blood flow and transferred oxygen are decreased as the plaques thicken the inner layer of artery wall. In atherosclerotic arteries, the diameter is typically decreased and the wall is stiffened by the blood plaques. In the minority cases, the artery can change its shape by increasing the outer diameter to accommodate a plaque. 7 In the other cases which include majority ones, the plaque aggregation causes to Atherosclerotic stenosis. 8 There is a speculation which notes that wall shear stress made by blood flow through its pulsatile inlet velocity leads to luminal thinning ∗ Author to whom correspondence should be addressed. a a stringy material that helps clot blood. and promotes plaque rupture that forms coronary thrombosis b , 9–11 Although scientists hesitate whether high haemodynamic shear alone would disrupt a stenotic plaque as haemodynamic stresses because of the fact that they are usually much smaller than mechanical stresses imposed by blood and pulse static pressures. This small piece of solid particles which block the path of blood flow causes people heart to suddenly stop working. In some cases this phenomenon can cause a heart attack if it completely blocks the blood flow in the heart arteries. 12 It can also cause a stroke if it completely blocks the brain arteries. Estimation of the reduc- tion in flow due to blood clots with high accuracy is important in determining their effects on angina and accurate estimation of the rise in the wall shear stress due to clots has suggestion and implications for the theory of plaque rupture. 13–15 Vascular fluid dynamics plays an influential role in the evolution and progres- sion of atherosclerosis. It has also been investigated that once a light clot is created, the resulting flow has further influence in the evolution of the disease with arterial abnormality shape resulting in considerable change in regional blood rheology. 16 17 So far, a considerable amount of theoretical and experimental works were carried out on this attractive and serious problem. These scientist efforts lead to discovering some of the mysteries about atherosclerosis. The effects of shear stress on the biologi- cal functions of endothelial cells c have been investigated on the several observations. These observations indicate that exposure b clot. c cells that lines the interior surface of blood vessels. Adv. Sci. Lett. Vol. 5, No. XX, 2011 1936-6612/2011/5/001/009 doi:10.1166/asl.2011.3274 1