Three Dimensional Analysis of the Blood Flow Regime within Abdominal Aortic Aneurysm

Abstract

Abdominal aortic aneurysm (AAA) is a degenerative disease, which is defined as the abnormal ballooning of the abdominal aorta (AA) wall usually caused by atherosclerosis. In the present work, finite-volume method for the numerical prediction of non-Newtonian blood flow patterns in AA is performed in the 3D model of AA with aneurysm along with its peripheral branches for systolic and diastolic cardiac phase. Grid independence was tested on three successively refined meshes. It is observed that the abrupt expansion induced by AAA results in an immensely disturbed regime, whereas aneurismal sac is characterized with a multiple vortices and reverse flow in both phases. However, in diastolic phase vortices and reverse flow is more random, and frequent in contrast to systolic phases but with lower kinetic energy. Immense pressure buildup between the renal and iliac bifurcation of AA is observed, that results in a velocity drop across aneurismal sac and unsteady flow at the iliac bifurcation which induces additional stress across the aneurysm. It believes that the pressure gradient is highly responsible for velocity drop, formation of emboli, and continued dilation of aneurismal sac that may result in the obstruction of a blood vessel leading towards rupture of the aneurysm.