Numerical Analysis of Multiphase Blood Flow within Carotid Artery & bifurcation using Mixture Model Theory

Abstract

CFD analysis of blood flow within the carotid artery has been carried out due to the rise of strokes and carotid artery diseases. The carotid artery is bifurcated into internal and external ones. Most of the earlier work has been done considering blood as a single phase. However, in this work, blood is treated as multiphase (plasma and morphotic particles). Finite difference method has been used to perform the numerical analysis, using a second-order time discretization scheme. Mixture model theory of Euler-Euler approach is preferred over the Eulerian model. Human blood shows Newtonian and non-Newtonian characteristics. During the cardiac cycle, it behaves non-Newtonian with a shear rate ranging from 0.1 to100 s-1, while Newtonian; exhibiting a shear rate more than 100 s-1. For the present analysis, it is mathematically modelled as an incompressible, time-dependent Newtonian fluid with average values of density and viscosity for each phase. A real geometry of the carotid artery was created using Computed Tomography Angiography image of a carotid artery and its bifurcation. Navier-Stokes equation has been solved computationally, with multiphase boundary conditions in ANSYS 19. CFD is a potent tool in analyzing blood flow within the treated artery. Especially after Carotid End-Arterectomy (CEA) and Carotid Angioplasty with Stenting (CAS) has been carried out. Moreover, an optimized stent design can be carried out using this work after analyzing the flow characteristics and in coordination with CT angiography results. Stent flow regimes and stent meshing can be studied to design a particular stent for a particular case.