Abstract:The fluid movement inside and outside a bubble rising in a liquid medium was investigated by taking the interfacial tension gradient and the potential variation along the bubble surface into account, then the potential distribution within the double layer and the electroneutral area outside the bubble was determined in order to get the normal and tangential potential gradient on the surface; Finally, a formula describing the electrophoretic mobility was reached, which is obviously distinct from that for solid particles and has been found to be in consistence with experimental results.

Key words: bubble　fluid recirculation　interface potential　electrophoretic mobility