Velocity profiles in symmetrically branched tubes simulating the aortic bifurcation

Abstract

The purpose of this study was to measure velocity profiles in a symmetrically branched tube with an area ratio (0.8) and angle of branching (70°) that were comparable to the bifurcation of the human descending aorta. Velocity profiles were measured in steady and pulsatile flow with a laser Doppler anemometer. In the branch near the vertex of the bifurcation the profiles were markedly skewed toward the inner wall during both steady and pulsatile flow. Points of inflection in the velocity profiles, where the profiles changed from convex to concave, occurred downstream from the vertex of the bifurcation. A region of transient flow reversal was found along the outer wall during minimal flow in the pulsatile cycle at mean Reynolds numbers below 1000. These observations are pertinent in understanding flow at bifurcations with a branch-to-trunk area ratio of less than one, as occurs at the aortic bifurcation.