Abstract
The structure of the flow around a rising bubble in silicone oil is experimentally studied by flow visualization using photochromic dye. The first experimental support for the existence of the standing eddy at the rear of the bubble, as predicted by a previous study by Ryskin and Leal [J. Fluid Mech. 148, 19-35 (1984)], was obtained in the case of high bubble aspect ratio χ . The drag coefficient of small bubble rising in this solution was compared with theoretical one derived by Mei [Phys. Fluids, 6, 418-420(1994)], and it is found that the bubble rising in this solution behaves as the “clean bubble". It is also shown that both the degree of the fore-aft asymmetry of the bubble shape and the size of standing eddy increases as the discrepancy in both rising velocity and drag coefficient between experimental results and Moore's theory [J. Fluid Mech. 23, 749-766 (1965)] increases.
