Simulation of near-wall bubble collapse and research on load mechanism of wall damage based on improved multi-relaxation-time lattice Boltzmann method

To reveal the load mechanism of wall damage induced by bubble collapse, the near-wall cavitation bubble collapse evolution is numerically simulated using an improved multi-relaxation-time lattice Boltzmann method (MRT-LBM), and the dynamic behavior of near-wall cavitation bubble is systematically analyzed. First, the improved multi-relaxation pseudopotential model with a modified force scheme is introduced and validated through the Laplace law and thermodynamic consistency. Subsequently, the near-wall bubble collapse evolution is simulated using the improved model, and the process of the bubble collapse evolution is obtained. The accuracy of the numerical simulation results is confirmed by comparing with previous experimental results. Based on the obtained flow field information, including velocity and pressure distributions, the dynamic behaviors during the bubble collapse are thoroughly analyzed. The results show that the micro-jets released during the near-wall bubble collapse primarily originate from the first collapse, while the shock waves are generated during both the first and the second collapse. Notably, the intensity of the shock waves produced during the second collapse is significantly higher than that during the first collapse. Furthermore, the distribution characteristics of pressure and velocity on the wall during the near-wall bubble collapse are analyzed, revealing the load mechanism of wall damage caused by bubble collapse. The results show that the wall is subjected to the combined effects of shock waves and micro-jets: shock waves cause large-area surface damage due to their extensive propagation range, whereas micro-jets lead to concentrated point damage with their localized high-velocity impact. In summary, this study elucidates the evolution of near-wall bubble collapse and the load mechanism of wall damage induced by bubble collapse, which provides theoretical support for further utilizing the cavitation effects and mitigation of cavitation-induced damage.