Flow dynamics in models of intracranial terminal aneurysms.

Flow dynamics play an important role in the pathogenesis and treatment of intracranial aneurysms. The evaluation of the velocity field in the aneurysm dome and neck is important for the correct placement of endovascular coils, and the temporal and spatial variations of wall shear stress in the aneurysm are correlated with its growth and rupture. This numerical investigation describes the hemodynamic in two models of terminal aneurysm of the basilar artery. Aneurysm models with a aspect ratio of 1.0 and 1.67 were studied. Each model was subject to physiological representative waveform of inflow for a mean Reynolds number of 560. The effects of symmetric and asymmetric outflow conditions in the branches were studied. The three dimensional continuity and Navier-Stokes equations for incompressible, unsteady laminar flow with Newtonian properties were solved with a commercial software using non structured fine grids with 197807 and 202515 tetrahedral cells for the model 1 and 2 respectively. The flow shows complex vortex structure in both models, the inflow and outflow zones in the aneurysm neck were determined. The wall shear stress on the aneurysm showed big temporal and spatial variations. The asymmetric outflow increased the wall shear stress on the aneurysm only in model 1.