Can the Flow Simulation Domain for Bifurcation Aneurysms on the Willis Circle Be Radically Reduced?

Abstract

This paper presents an attempt to decrease the domain for the simulation of blood flow in certain types of bifurcation aneurysms. A reduced computational cost would be beneficial for the simulation of large datasets, to have statistical data for various hemodynamical parameters. The reduction is achieved by cutting the geometry in an objective manner, with the help of the Vascular Modelling Toolkit (VMTK). CFD simulations were carried out on both the original and the partial geometries, using partially patient-specific boundary conditions. The post-processing focused on the velocity field, as it is more robust than the wall shear stress-based indicators for aneurysm formation. Using VMTK, a centerline was calculated for each case. Various morphological values can be calculated, namely the torsion and curvature. The velocity field was broken down to velocity components using the Frenet-frames. The evaluation was carried out on a plane before the next bifurcation downstream. The post-processing calculations were made for 2 distinct time steps, one at the systolic and one at the diastolic instant and for a cycle average. The results showed that the method reproduces the axial velocity component with small deviations. However, for the secondary components the difference between the partial and original geometries was unacceptably high. Therefore, the method proved to be unsuitable.