Arterial fluid flow investigation on double stenoses contact morphology for medical application

Abstract

Fluid flow investigation has been constantly worked upon since the dawn of Microelectromechanical Systems (MEMS) devices. Human vascular system provides the means for MEMS transportation thus enabling study and analysis on human diseases. Atherosclerosis is a vascular disease characterized by deposition of plaques on the arterial wall. The progression of atherosclerotic plaques may cause serious consequences due to disturbance of the blood flow such as heart attack and stroke. Therefore, the study of the fluid dynamics in the stenosed artery bears important aspects to predict the development of atherosclerosis. In this research, the Newtonian fluid through double stenoses has been investigated using Ansys CFX software. To study the effects of stenosis morphology, three different geometries have been used; cosineshaped, irregular shape and protruding shape. These geometries present different area occlusion but similar configurations of stricture length and height. On the other hand, the effects of restriction spacing have been explored by varying the distance between the double stenoses without changing the size of each stenosis. The effects of Reynolds numbers have been investigated as well in the range of 100 to 400 based on human physiological flow. Hemodynamic characteristics of blood flow such as velocity profiles, wall pressure and wall shear stress distributions have been performed for all cases. The results demonstrate highest peak velocity, pressure drop and peak wall shear stress with the value of 0.7518 ms-1, 398.16 Nm-2 and 15.39 Nm-2 respectively for the case of double irregular stenoses. It is interesting to find out that double protrudingshaped stenoses exhibit greater peak velocity (0.672 ms-1) and peak wall shear stress (14.90 Nm-2) in comparison with cosine-shaped stenosis with peak velocity, 0.6578 ms-1 and peak wall shear stress, 13.06 Nm-2 although the area occlusion of cosine shaped is larger instead. These findings indicate that the severity of the stenosis is primarily caused by the morphology of the stenosis rather than percentage of diameter reduction criterion or effects of area occlusion. Analysis on the effects of restriction spacing shows that the distance between a couple of stenoses has a considerable influence on the velocity profile, wall pressure distribution and wall shear stress variation. In addition, the effects of Reynolds numbers are noticeable in changing the flow pattern near the stenotic region whereby the higher Reynolds numbers increase the size of recirculation zone. The recirculation zones usually occur in the severe stenosed artery. In conclusion, the present study shows that the blood flow characteristics through double stenoses are strongly influenced by the stenosis morphology, restriction spacing and Reynolds numbers