The objective of this research is the determination of the wall shear stress (WSS) and velocity distribution patterns in axi-symmetric single or repeated stenoses in coronary arteries. The blood flow is modeled as an incompressible laminar flow with Re = 500 and the analysis is performed for both Newtonian and non-Newtonian blood behaviors. For the single stenosis cases, the area reduction of 25%, 64% and 75% are considered, while for the consecutive stenosis cases two sets of 64%, 25%, and 75%, 64% for the first and second stenosis are examined numerically respectively. Single stenosis cases are also employed for validation purposes, since experimental data are available for them. Present results indicate that regions of high and low shear stress may play an important role in the rupture of atherosclerotic lesions. Both sides of the stenotic area with high WSS and intense WSSG (Wall Shear Stress Gradient) are the most vulnerable sites of plaques. For the cases of consecutive stenoses, results show that displacement of the secondary plauque does not have any effect on the flow pattern. Moreover, the effect of the progression and the area reduction percentage of the consecutive stenoses were studied numerically. It was concluded that the progression of the first and the second stenoses creates high alterations in WSS and velocity distribution and increases the vulnerability of creation of new plaques. Furthermore, the pulsatile property of blood was considered. An accurate velocity waveform was implemented to predict the pulsatile behavior of blood. Results significantly vary from those of the laminar analysis in terms of velocity distribution and the magnitude of the maximum velocity. The flow patterns are studied for several time sections in one period.

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