Abstract
Mechanism of bubble coalescence is not clear. It is one of the unknown problems in multiphase flow phenomena. Recently, the utilization of microbubble becomes a key technology in both mechanical and chemical engineering fields. In general, it is believed that the microbubble is hard to coalesce with each other unlike bubbles of millimeter size. However, we found many microbubble coalescences in the microbubbly flow. Until today, the microbubble coalescence has not been reported via the experimental observations, and there is no theory that can explain the mechanism of the bubble coalescence in all bubble scale. Our observation reported here overrides the conventional conception and this fact is important for both engineering and academic fields. The purpose of this paper is to report our findings by using the high-speed camera, and to try to elucidate the mechanism of the microbubble coalescence.
