Abstract
When bubbles rise through a liquid-liquid (water-oil) interface, the lower liquid is entrained into the upper liquid. Many water droplets are generated in oil layer, and they influence the phenomena of heat and mass transfer between the liquids.
In the experiments, silicone oil of 1 cSt is poured on water with 100mm depth. By utilizing a high-speed and hi-resolution video camera, it is found that there are three different processes in generating droplets. The largest class of droplets originated from entrained water columns, while the second class ones were born when penetrating water jets break. The jet appears when water film, which wraps up a bubble, is broken and slips down to a bottom of the bubble. The smallest droplets appear in the vicinity of bubbles when entrained water leaves bubbles.
