SIMULATION OF THE COLLAPSE EVOLUTION OF ATTACHED CAVITATION BUBBLE AND STUDY ON THE MECHANISM OF WALL WETTABILITY BASED ON IMPROVED MULTI RELAXATION PSEUDO POTENTIAL MODEL

Combined with the improved multi-relaxation pseudo-potential model, the lattice Boltzmann method was used to numerically simulate and analyze the evolution process of the collapse of attached cavitation bubble, with a focus on studying the influences of wall wettability on the collapse of attached cavitation bubble. First, a thermodynamic consistency verification was conducted on the improved multi-relaxation pseudo-potential model. By comparing the numerical and analytical solutions of gas-liquid coexistence density, the parameters that satisfy the thermodynamic consistency requirements were chosen to enable the model to achieve numerical computation of multiphase flows with a large density ratio. Then, the equilibrium contact angle of attached cavitation bubble was numerically simulated for different wall wettability, and the relationship between wall wettability and the equilibrium contact angle of attached cavitation bubbles was analyzed. The analysis show that the equilibrium contact angle gradually increases and the wall wetting ability gradually becomes weaken, as the interaction strength between the wall and the fluid increase. Further, the collapse process of attached cavitation bubble was modeled, and the corresponding boundary formats were processed to complete the numerical calculation of the collapse of attached cavitation bubble. The influence of different wall wetting conditions on the collapse of attached cavitation bubble was analyzed in detail. The analysis show that the enhancement of wall hydrophobicity shortens the collapse time when the initial pressure difference and morphology of the cavitation bubble are the same. In particular, as the wall wettability gradually changed from hydrophilic to hydrophobic, the maximum collapse pressure decreases first and then gradually increases, while the maximum collapse velocity continued to increase with the enhancement of the wall hydrophobicity. The results reveal the influence law of wall wettability on the collapse of attached cavitation bubble, providing theoretical guidance for further suppressing the destructive effects of the collapse of attached cavitation bubble and the engineering application of utilizing the cavitation bubble collapse effects.