A numerical investigation on the steady and pulsatile flow characteristicsin axi-symmetric abdominal aortic aneurysm models with some experimental evaluation

Steady and pulsatile flow characteristics in rigid abdominal aortic aneurys m (AAA) models were investigated computationally (using Fluent v.4.3) over a range of Reynolds number Vi-om 200 to 1600) and Womersley number (from 17 to 22). Some comparisons with measurements obtained by particle image velo cimetry under the pulsatile flow conditions are also included. A sinusoidal inlet flow waveform 1+sin omega t with thin inlet boundary layers was used to produce the required pulsatile flow conditions. The bulk features of th e mean flow as well as some detailed features, such as wall shear stress di stributions, are the foci of the present investigation. Recirculating vorti ces appeared at different phases of a flow cycle causing significant spatia l and temporal variations in wall shear stresses and static pressure distri butions. A high level of shear stresses usually appeared at the upstream an d downstream ends of the bulge. Effects of pressure rise caused by the incr ease in cross-sectional area were transmitted into the downstream tube. Fur ther simulation studies were conducted using simulated physiological wavefo rms under resting and exercise conditions so as to determine the possible i mplication of vortex dynamics inside the AAA model.