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

Abstract

Flow characteristics in Abdominal Aortic Aneruysm models have been investigated using Particle Image Velocimetry over a range of Reynolds numbers (from 400 to 1400) and Womersley numbers (from 17 to 22). Both steady and pulsatile flow experiments have been conducted. For the pulsatile flow, a sinusodial inlet flow waveform 1 + sin ωt was used. It was found that under the steady flow conditions, a recirculating vortex occupied the entire circular bulge with its core located closer to the distal end of the bulge. The strength of the vortex would increase as the Reynolds number increased but would not exceed more than 10% of the bulk flow in the parent tube. Under the pulsatile flow conditions, the vortex appeared initially near the proximal end 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 in the transverse direction with higher strength. The vortex was convected slowly towards the distal end of the bulge by the bulk flow and an abrupt drop in its strength appeared when it reached there. Attempts have been made to explain the flow development using vortex dynamics.