Investigating the influence of rheology and morphology on hemodynamics in intracranial aneurysms: A CFD study

Computational fluid dynamics (CFD) simulations are essential for understanding the complex flow dynamics involved in the formation and rupture of cerebral aneurysms. Interventional neurosurgeons and clinicians continually seek to identify the factors that contribute to aneurysm rupture. While numerous CFD studies have previously examined the influence of morphology and hemodynamics, the correlation between these factors requires further investigation. This includes a critical evaluation of boundary conditions and assumptions, such as blood viscosity, inlet velocity profiles, and geometric idealizations, used in previous work. Although blood exhibits non-Newtonian behavior, many researchers have simplified their models by assuming Newtonian fluid properties for computational efficiency. In this study, the authors performed CFD simulations of blood flow in five idealized aneurysm models, employing both Newtonian and non-Newtonian (Carreau) viscosity models, to analyze the relationship between aneurysm morphology, viscosity models, and hemodynamic stresses. Results of the present work reveal significant fluctuations in hemodynamic parameters during both systolic and diastolic phases across all models, with minimal variation in wall shear stress (WSS) during both systole and diastole. WSS increased linearly with aneurysm size from 7 to 15 mm in both Newtonian and non-Newtonian models, then gradually decreased in aneurysms larger than 15 mm. The difference in WSS values between the Newtonian and Carreau models was more pronounced in aneurysms smaller than 15 mm, becoming negligible in larger aneurysms. Therefore, a more comprehensive investigation is warranted to fully elucidate flow dynamics in aneurysms exceeding 15 mm in diameter.