Distribution of WSS on the Internal Carotid Artery With an Aneurysm: A CFD Sensitivity Study

Intracranial blood flow simulations for studying brain aneurysms are based on many assumptions including the Womersley profile for the inlet boundary condition. Moreover, computational domains seem to be more or less arbitrarily chosen. Previous studies have shown that long inlet vessels lead to more realistic flow just upstream of the aneurysm. In order to guide our studies of cerebral aneurysms, using the high-order spectral/hp element method, we systematically investigated the geometric sensitivity of wall shear stress (WSS) on aneurysms; specifically, the effect of parent vessel geometry on the WSS in aneurysms was considered. Using datasets of two patients with different type of aneurysms, five different geometric models were generated. With the aneurysm geometries fixed, the length or turning angles of inlet parent vessel were varied one at a time. This study demonstrates that the turning angle of upstream blood vessel, the type of aneurysm, and its location with respect to the parent vessel affect the distribution of WSS in the aneurysm. In the fusiform aneurysm with sharp turns, the inlet length makes a substantial difference on impinging location, magnitude, and direction of WSS. On the other hand, the saccular type aneurysm with a smoother parent vessel does not show any significant change. Therefore, the computational domain should be determined based on the geometry of parent vessels and the type of aneurysm.