4223 静止液体中での2気泡の合体および反発(G05-12 気泡・液滴(1),G05 流体工学)  [in Japanese] 4223 Bouncing and Coalescence of a pair of Bubbles in a Quiescent Liquid  [in Japanese]

We experimentally studied both bouncing and coalescence of a pair of bubbles rising side by side in a quiescent liquid. At high Reynolds number, a pair of bubbles approached each other and then collided. After the collision, bubbles either coalesced or bounced. We visualized flow field formed in the vicinity of bubbles by irradiating photochromic dye with UV light sheet, and observed wake of bubbles both before and after the collision. We discuss wake development of bubbles as bubbles collided and the relation between wake structure and bubble motion after the collision. We also investigated the critical Reynolds number and Weber number of coalescence of bubbles. We clarified that the critical Weber number is approximately two regardless of Morton number and that the critical Reynolds number decreases with the increase in Morton number.