Abstract
The structure of the flow around a rising bubble in silicone oil was visualized by using photochromic dye. We present the first experimental evidence of the existence of the standing eddy, which was predicted numerically by Blanco & Magnaudet[Phys. Fluids, Vol.7, 1265-1274(1995)]. We also experimentally evaluated two kinds of critical aspect ratios over which the standing eddy or three dimensional wake exists. It was found that experimentally obtained critical aspect ratios were smaller than those obtained numerically, however both experimental and numerical results qualitatively agree that critical aspect ratios were bigger in lower Reynolds number.
