Mass deposition and fluid flow in stenotic arteries: Rectangular and half-circular models

Mass deposition inside the artery wall may play a significant role in the development of the disease atherosclerosis. Locally elevated concentrations of LDL in the arterial wall are considered to be the initiator of atherosclerotic plaque formation. In this study, an attempt has been made to study initially the effect of fluid dynamic parameters on the disease and finally proposed a concept, from the idea of basic flow characteristics in constricted arteries, for the assessment of mass deposition in the arterial wall to some extent for rectangular as well as half circular stenosed models. Reynolds numbers are chosen as 100, 200, 300 and 400 and percentage of restrictions as 30%, 50%, 70% and 90% respectively. The governing Navier-Stokes and continuity equations are solved in the artery lumen with the commercial CFD code ANSYS 12.1. The pressure-velocity coupling equations are solved by SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) algorithm. The studies on pressure drop at stenosis zone and flow separation zone reveal that the effect of percentage of restriction is more dominant than Reynolds number on the progression of the disease, atherosclerosis for any shaped restriction. The mass deposition results of rectangular and half circular stenotic models motivate to conclude that the effect of percentage of restriction is more prone to the disease than that of Reynolds number. Half circular stenotic shape insists for the less chance of mass deposition in the arterial wall compared to rectangular shaped restriction.

Pressure Characteristics Study for the Configuration of Sudden Expansion with Central Restriction and Suction

In this paper, an extensive numerical study on pressure characteristics in the configuration of sudden expansion with central restriction and suction has been carried out. During study, Reynolds numbers (Re) are considered from 50 to 200, suction (S) from 2% to 10% of inlet mass flow, percentage of central restriction (CR) from 0% to 40% and aspect ratio (AR) from 2 to 6. The effects of each variable on average static pressure distribution and average stagnation pressure distribution have been studied in detail. The results have been compared with the configuration of plain sudden expansion, and sudden expansion with central restriction only. From the study, it is noted that maximum magnitude of average static pressure rise from throat increases with the increase in percentage of suction, flow Reynolds number and percentage of central restriction. This magnitude is higher at lower aspect ratio. Also, it is observed that maximum magnitude of average static pressure rise from throat is always more in case of suction configuration compared to the case of configuration of without suction. Average stagnation pressure drop at any section increases with the increase in percentage of suction and percentage of central restriction, but it decreases with the increase in Reynolds number. It is noted that higher pressure drop at any section occurs at higher aspect ratio. This pressure drop at a section is more in case of suction configuration compared to the case of without suction.