Blood Flow Simulations of Particle Trapping in Models of Arterial Bifurcations

Abstract

This paper describes the particle trapping mechanism in blood flow in different arterial bifurcation models. For validation of CFD calculations, a T-junction model and a Y-junction model are analyzed. In both the models, there is one inlet pipe with two outlet pipes creating a symmetric bifurcation at some angle from the centerline of the inlet pipe. Naiver-Stokes (RANS) equations are solved for single phase laminar flow using the commercial CFD software ANSYS Fluent. After validation, Eulerian simulations are performed by using the Discrete Phase Model (DPM) for two-phase flow with particles injected in different bifurcation models with bifurcation angle of an outlet pipe varying from 80° to 100° w.r.t the centerline of the inlet pipe (90° being the bifurcation angle of T-junction). By changing the average Reynolds number of the flow and the injected particle diameters, the mechanism of particle trapping is investigated in laminar flow. The contours of velocity magnitude, pressure and wall shear stress are also obtained and analyzed. It is found that the particle trapping increases as the bifurcation angle decreases from 90° and becomes negligible as the bifurcation angle increases from 90°. This is a very important result which has never been reported in the previous literature. In addition, turbulent flow computations for T-junction flow are performed using the SST k-ω and Wray-Agarwal turbulence models. Finally, the influence of stenosis in Y-junction is studied and analyzed. The results have implications in understanding the hemodynamic flows in arterial bifurcations without and with stenosis.