Comparative Study of Rheological Models for Pulsatile Blood Flow in Realistic Aortic Arch Aneurysm Geometry by Numerical Computer Simulation

Abstract

In numerical simulations of blood flow in the aorta, shear rates tend to be higher than 100 s - 1, making blood behave as a Newtonian fluid, with constant dynamic viscosity. This study proposes a comparative analysis via computational fluid dynamics (CFD) of the Newtonian, Carreau-Yasuda, Power-Law and Casson rheological models for a realistic geometry of the aortic arch obtained by computed tomography (CT) and adapted with an aneurysm. It has been shown that there are instants of time throughout the cardiac cycle in which the blood exhibits non-Newtonian behavior. This behavior leads to a considerable variation in the dynamic viscosity that can influence the flow hemodynamics. It was also possible to detect that the effective viscosity varies over the cardiac cycle, including the Newtonian model, which suggests that the turbulent viscosity is variable. In general, the Carreau-Yasuda and Power-Law models show similar behavior, whereas the Casson model tends to be more closely to the Newtonian model.