Effect of Various Geometrical Properties of Carotid Artery on the Flow by Computational Fluid Dynamics

The risk of capsular rupture increases with high wall shear stress (WSS), and the location of the high WSS can be predicted using Computational Fluid Dynamics (CFD). Most previous studies have not been evaluated the quantity and validate the CFD results. Therefore, it is necessary to establish a proper evaluation method that includes the variance of normal carotid arteries. In this study, variances of the normal carotid artery are investigated by analysing geometrical properties, and a standard model is established by averaging various geometries. Further, the geometrical properties of standard model are changed in the range of normal variance, and the effect of the change of geometries on the evaluation indexes such as time-averaged WSS are investigated. Three-dimensional models of normal carotid arteries are constructed by using 2D-CT images, and the standard model is established by averaging various geometries. The diameter of the common carotid artery DC is changed in the range of 5~9 mm and the bifurcation angle θ is changed in the range of 50~70°. Continuity and Navier–Stokes equations are used because the flow is assumed to be incompressible and laminar. The inlet boundary condition is set such that the distribution is a fully developed velocity based on the averaged velocity waveform. The outlet boundary conditions include atmospheric pressure (= 0 Pa), and the wall boundary condition includes the use of no-slip conditions. The WSS in the bifurcation region increases approximately 23% with a larger bifurcation angle, which can be attributed to the force on the wall increasing when the fluid collides with the bifurcation region. In addition, the sensitivity of the bifurcation angle was larger than the sensitivity of the diameter, which is a result useful for comparing the analysis results of each patient.