Numerical simulation of pulsatile flow with newtonian and non-newtonian behavior in arterial stenosis

There is considerable evidence that vascular fluid dynamics plays an important role in the development and prevalence of atherosclerosis which is one of the most widespread disease in humans .The onset and prevalence of atherosclerosis hemodynamic parameter are largely affected by geometric parameters. If any obstacle interferes with the blood flow, the above parameters change dramatically. Most of the arterial diseases, such as atherosclerosis, occur in the arteries with complex patterns of fluid flow where the blood dynamics plays an important role. Arterial stenosis mostly occurs in an area with a complex pattern of fluid flow, such as coronary artery, aorta bifurcation, carotid and vessels of lower limbs. During the past three decades, many experimental studies have been performed on the hemodynamic role of the blood in forming sediment in the inner wall of the vessels. It has been shown that forming sediment in the inner wall of vessels depends on the velocity of fluid and also on the amount of wall shear stress.We have examined the effect on the blood flow of local stenosis in carotid artery in numerical form using the incompressible Navier-Stockes equations. The profile of the velocity in different parts and times in the pulsatile cycle, separation and reattachment points on the wall, the distance stability of flow and also alteration caused by the wall shear stress in entire vessel were shown and compared with two behaviors flow [Newtonian and Non-Newtonian].Finally we describe the influence of the severity of the stenosis on the separation and reattachment points for a Non-Newtonian fuid. In the present study, we have pointed very low and high oscillating WSS [Wall Shear Stress] values play a significant role in the development of forming sediment in the inner wall of vessels. Also, we obtain this probability is higher for Newtonian than Non-Newtonian fluid behavior.Based on our results, the possibility of the endothelium destruction is greater with the Newtonian fluid behavior and in the regions where WSS are beyond the range of 10-420 dyne/cm2

[ effect of flow divider on restenosis in stented human coronary artery with modelling]

Shear stress is known to play a central role in restenosis formation and is sensitive to stent geometry. To investigate the effect of flow divider on restenosis in a stented human coronary artery. The present paper describes a qualitative study in which a computational fluid dynamics model to analyze the blood flow in a stented human coronary artery was used. Stents were assumed with real structure and modeled using the commercial software package [Gambit, V2.0]. A flow divider is a flexible cylindrical body with different diameters and lengths which is centered within the stent lumen by means of self-expandable stabilizing arms. The blood flow was modeled as an incompressible Newtonian viscous fluid. Rigid geometric boundary conditions were assumed for all simulations. The governing equations were solved using the commercial software package [Fluent, V6.0.12]. The wall shear stress between stent struts was sensitive to the flow divider, and the wall shear stress distributions for different types of flow divider were calculated. Application of a flow divider led to noticeable increase in wall shear stress in stented segment