VOF-DEM numerical study of mesoscale bubble dynamics in the gas-liquid-solid three-phase flow system

Mesoscale bubble dynamics play a critical role in governing the overall performance of gas-liquid-solid systems. In this study, the volume of fluid method coupled with a discrete element method is utilized to scrutinize the mesoscale bubble dynamics within a gas-liquid-solid system featuring a dense particle bed. The results reveal that the squeezing effect of the particle bed induces a bubble pairs regime, which causes the bubble collision, coalescence and breakup, thereby generating daughter bubbles. Additionally, the combined influence of large size, flattened shape, off-center collisions and the exists of particles facilitate bubble wakes to transform from closed into asymmetrical open patterns, further causing particles released from bubble wakes. Finally, the high-speed region is predominantly confined to the bubble wake area, resulting in a diminished overall stirring capability compared with two-phase system. The insights obtained from this study shed valuable light on bubble behaviors within gas-liquid-solid systems, offering implications for further study in this field.