Comparison of newtonian and non-newtonian models using computational fluid dynamics in cerebral aneurysms: analysis of two patient-specific cases

Abstract

The rupture of cerebral aneurysms represents a serious health threat, associated with high rates of mortality and morbidity. In this context, understanding the underlying pathological mechanisms is essential to improve patient evaluation and clinical management. In particular, wall shear stress (WSS) plays a key role in the formation, progression, and rupture of aneurysms. This study investigates the impact of the blood constitutive model on WSS estimation through numerical simulations of fluid dynamics in two patient-specific aneurysm geometries. Specifically, the classical newtonian model is compared against the non-newtonian Casson model, using physiologically realistic boundary conditions reported in the literature. Additionally, a methodology for generating computational domains is proposed. Results show that differences in WSS between both models remain below 3.5% throughout the cardiac cycle, both in the dome and the neck of the aneurysms. It is concluded that, under the simulated conditions, the newtonian model provides a reliable approximation for estimating WSS, reducing computational cost without compromising accuracy.