Steady and pulsatile flow studies in Abdominal Aortic Aneurysm models using Particle Image Velocimetry

Flow characteristics in Abdominal Aortic Aneruysm models have been investig ated using Particle Image Velocimetry over a range of Reynolds numbers (fro m 400 to 1400) and Womersley numbers (from 17 to 22). Both steady and pulsa tile flow experiments have been conducted. For the pulsatile flow, a sinuso dial inlet flow waveform 1 + sin wt was used. It was found that under the s teady flow conditions, a recirculating vortex occupied the entire circular bulge with its core located closer to the distal end of the bulge. The stre ngth of the vortex would increase as the Reynolds number increased but woul d not exceed more than 10% of the bulk flow in the parent tube. Under the p ulsatile flow conditions, the vortex appeared initially near the proximal e nd of the bulge at the early stage of a flow cycle, occupying approximately 1/4 of the bulge. The subsequent deceleration of the bulk flow caused the vortex to reduce its extent in the direction of the flow but was enlarged i n the transverse direction with higher strength. The vortex was convected s lowly towards the distal end of the bulge by the bulk flow and an abrupt dr op in its strength appeared when it reached there. Attempts have been made to explain the flow development using vortex dynamics. (C) 2000 Elsevier Sc ience Inc. All rights reserved.