Computational fluid dynamics of the human cerebral circulation system: A biological perspective

Abstract

A cerebral aneurysm is a vascular disease causing the structure of arteries to weaken and over time to bulge outward. Rupture of such aneurysms cause intracranial bleeding that can be fatal or signifi cantly impact the patient's life quality. This report investigates the initiation, growth and rupture of cerebral aneurysms. The objective of this thesis is to analyse the biological connection between cerebral aneurysms and the associated blood flow characteristics. By using MRI pictures from a healthy individual's brain, a geometry construction made in MATLAB is used for simulation of the blood flow in arteries using computational fluid dynamics (CFD). The simulations focus on the velocity of the blood flow and the shear stress, and how they vary with different blood models, Newtonian and non-Newtonian, and with and without the presence of an artifi cial aneurysm. The results show that areas more prone to develop aneurysms show higher values of shear stress supporting the connection between high wall shear stress and aneurysm initiation. The results also indicate that the presence of an aneurysm affects the fluid dynamics, whose characteristics depend on whether the simulations are based on the Newtonian or non-Newtonian model. In the search of regions at risk for aneurysm initiation, it is suggested that the non-Newtonian model is more preferable in particular due to the ability to include the shear thinning effect.