Investigations of Aspect Ratio Effects on Wake Dynamics of Rectangular Cylinders

Abstract In this paper, the flow characteristics around rectangular cylinders with different length to height ratios (aspect ratios, AR) of AR1, AR2, AR3 and AR4 are studied using a particle image velocimetry. The Reynolds number (Re) was 7200 in all cases and the results were analyzed in terms of the mean flow characteristics, Reynolds stresses and triple velocity correlations. The separated flow did not reattach for AR1 and AR2 cylinders. The flow topology around the AR2 cylinder showed a massive wake vortex compared to the other tested cases. The recovery of the mean velocity within the wake region was slowest for AR2, meanwhile, AR3 and AR4 revealed mean reattachment over the cylinder. The magnitudes of the Reynolds stresses and triple velocity correlations were consistently higher along the cylinder centerline for AR1 compared to the other cases.