Hemodynamic behavior analysis of Fusiform Aneurysms under Pulsatile Flow with Shear-Dependent Blood Rheology

Abstract

Bio-mechanical and hemodynamical changes happen due to fusiform aneurysms which alter flow structure and shear stress distribution along the affected segment. This study applies three-dimensional CFD analysis to investigate the hemodynamic environment associated with fusiform aneurysms under physiologically realistic pulsatile blood flow. Numerical simulations are performed in COMSOL Multiphysics using finite element methods, incorporating both Newtonian and Carreau non-Newtonian rheology to evaluate the influence of blood viscosity behavior. Key hemodynamic quantities velocity fields, pressure distribution, WSS, OSI, TAWSS, and RRT are quantified to characterize the flow response to the elongated aneurysmal deformation. Peak systolic velocity is 0.87% lower in the Carreau model compared to the Newtonian model, while diastolic velocity decreases by 11.6%. Peak WSS at systole differs by approximately 9.75% between models, whereas the minimum TAWSS in the aneurysm sac is up to 9% lower under Carreau rheology. The maximum OSI in the sac increases by 0.87% for the non-Newtonian case, indicating greater flow reversal sensitivity, and the maximum RRT increases by roughly 2.6%, suggesting enlarged thrombus-prone zones. These findings demonstrate that the choice of rheological model significantly influences diastolic-phase hemodynamics and thrombus risk indicators, underscoring the importance of non-Newtonian modeling for accurate fusiform aneurysm assessment.