Numerical Analysis Of Pulsatile Blood Flow In Abdominal Aortic Aneurysm (Aaa Disease)

Abstract

A numerical investigation based on dual grid has been presented for simulation of blood flow, behaving as non-Newtonian fluid flowing through Abdominal Aorta containing aneurysm on a non- body fitted axisymmetric computational grid. A cut cell based immersed boundary method (IBM) has been used to sharply resolve damaged abdominal aorta, and analyse the fluid behaviour, and its properties. The cut cell near the immersed boundary are identified using a fictious level set function. The governing equations has been discretized using the Finite Volume Method (FVM) on m x n staggered grid. Realistic aortic blood flow condition has been provided using pulsatile inlet velocity. To mimic the characteristic of blood generalized non-Newtonian (Carreau Yasuda) model has been used. Numerical investigation on aneurysm leading to increment of vessel diameter by 50%, 75% and 95% greater than the normal vessel diameter (2cm), as from the studies it has been found AAA is confirmed after 50% enlargement and surgery is recommended for 75% enlargement compared to normal aorta. For these conditions Wall Shear Stress (WSS), Time Averaged WSS and Space Averaged WSS along with skin friction coefficient (SFC), pressure drop across the domain and parameters leading to a better study of fluid properties has been carried out. If surgery was not carried out, when recommended, what will be the critical factors, in which significant changes can be seen, has been presented. As the presence of aneurysm will lead to change in wave flow velocity due to change in pulse rate, a parametric study of the fluid properties at different pulse rate has been presented, assuming wall to be rigid. Study has been carried out so that relation of pulse rate with vessel diameter containing aneurysm diameter can be presented, which shows critical region.