Multiple vapor cavitation bubble interactions with a thermal lattice Boltzmann method

The double distribution function thermal lattice Boltzmann method is applied to investigate the thermodynamics of bubble interactions. The complete growth and collapse processes during an interaction are successfully reproduced, and interaction regimes of double cavitation bubbles are systematically studied, including strong and weak interactions. The critical distances to distinguish different interaction modes between two equal-sized bubbles are also proposed. For the weak interaction regime of two unequal-sized bubbles, the pressure wave generated by the smaller cavitation bubble leads to less distortion of the larger bubble in the final collapse stage. Moreover, a modified inertia model is proposed, which can be used to predict the liquid film thickness evolution of the unequal-sized bubbles under strong interaction regimes. Unbalanced forces act on the liquid film for two unequal-sized bubbles, making the film more difficult to rupture than for equal-sized bubbles, and the coales-cence regime needs a smaller initial distance between them. Finally, the "shield effect" of the outer layer cavitation bubble and the "wall effect" of inner layer cavitation bubbles have been accurately reproduced in a cavitation bubble cluster, and the toroidal bubble shape in the final collapse stage is successfully simulated.