Numerical Study on Bubble Coalescence and Breakup in Two-Phase Flows Inside a Small Container

This study employed Eulerian-PBM analysis to investigate the flow phenomena in which bubbles from a bubble generator coalesce and break up in a tank. A 1 l tank model was optimally represented. Based on the bubble size and dispersion range observed in the experiment, and by varying the bubble size introduced through this structure, 20 µm bubbles were found to coalesce into larger bubbles near the water surface, reducing the volume fraction in the tank due to degassing. The number density of bubbles in the tank increased rapidly at an injected flow rate of 1.1 l/min . Additionally, as the volume fraction of injected bubbles increased, internal circulation caused more active bubble diffusion, further increasing the number density of bubbles in the tank. However, as the size of the injected bubbles increased during the flow, they coalesced into larger bubbles, resulting in a decrease in number density.