Implosion of a bubble pair near a solid surface

The accidental implosions of pressure vessels in the deep ocean may cause severe damage to the surrounding structures, and the induced liquid jet and shock wave can even lead to a chain reaction of nearby pressure vessels. Since the whole physical process can be approximately reproduced by the inertial collapse of air bubbles, in this study, the collapse of two adjacent bubbles near a solid wall is considered as an analog to assess the implosions of pressure vessels. An adaptive mesh refinement solver is developed for the high-fidelity simulation of the compressible multiphase flows. First, the implosion of a single bubble and the explosion of two bubbles are simulated for numerical validation. Then the collapsing process of two equal-sized bubbles with a different arrangement is simulated. By the advantage of the present numerical technique, the sharp shock fronts emitted from the collapse are captured with high resolution, and the high wall pressure induced by the shock wave is investigated in detail. Numerical results reveal that the wall-bubble distance and the bubble-bubble distance are crucial for the shock-impacting wall pressure and the jet flow direction. It is found that the maximum wall pressure occurs when the two bubbles are horizontally arranged in relation to the solid wall, while the perpendicular arrangement leads to the lowest wall pressure. The present findings of the two-bubble collapse are significant in determining the arrangement of pressure vessels inside submersible structures.