Numerical investigation of the time-resolved bubble cluster dynamics by using the interface capturing method of multiphase flow approach

The present paper proposes a multiphase flow approach for capturing the time-resolved collapse course of bubble clusters in various geometrical configurations. The simulation method is first verified by computing the dynamic behavior of an isolated vapor bubble placed in a uniform ambient pressure. The comparison between the numerical result and the theoretical solution indicates that the method can accurately capture the bubble shape, the characteristic time and the extremely high pressure induced by the collapse. Then the simulation method is applied to investigate the behavior of two kinds of bubble clusters in hexagonal and cubic geometrical configurations. The predicted collapsing sequence and the shape characteristics of the bubbles are generally in agreement with the experimental results. The bubbles transform and break from the outer layer toward the inner layers. In each layer, the bubbles on the corner first change into a pea shape and cave before collapsing, then the bubbles on the sides begin to shrink. It is also found that, in comparison with the case of an isolated single bubble, the central bubble in the cluster always contracts more slowly at the early stage and collapses more violently at the final stage.