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Numerical simulations of bifurcation cerebral aneurysm hemodynamics Asgari, Hanie

Abstract

A cerebral aneurysm is a dilation of a brain artery wall occurring more frequently in the circle of Willis. The cerebral aneurysm rupture is a life-threatening incident with a high mortality rate that requires emergency medical treatment. To accurately predict the growth and rupture of cerebral aneurysms, understanding the hemodynamics characteristics is of great importance. A comprehensive study regarding the combined effect of the aneurysm size and bifurcation artery angle on the aneurysm rupture risk is still missing. In patient specific geometries, the bifurcation arteries are not completely perpendicular to the parent arteries, therefore, it is essential to investigate the effect of different bifurcation artery angles on the hemodynamics of cerebral aneurysms. In the present thesis, the physiologically realistic pulsatile Newtonian and non-Newtonian blood flow conditions are numerically simulated in idealized aneurysms with different geometric features defined by the size of the aneurysm and the bifurcation artery angle to investigate the aneurysm rupture risk. The current study also considers the blood flow dynamics simulation in a patient-specific cerebral aneurysm geometry to examine the hemodynamics behavior of a real cerebral aneurysm. The results indicate that blood flow is more unstable under the Newtonian blood assumption as there are stronger viscous forces that prevent fluid flow from instabilities under non-Newtonian assumptions. Furthermore, it is seen that the aneurysm size and bifurcation artery angle have a considerable effect on aneurysmal inflow which is an important factor in cerebral aneurysm treatment. Comparison of the wall shear stress distribution in the patient-specific geometry and the idealized geometry indicates that idealized geometries can predict the real aneurysm hemodynamics characteristics with acceptable errors.

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