Investigation of cavitation bubble collapse in hydrophobic concave using the pseudopotential multi-relaxation-time lattice Boltzmann method*

The interaction between cavitation bubble and solid surface is a fundamental topic which is deeply concerned for the utilization or avoidance of cavitation effect. The complexity of this topic is that the cavitation bubble collapse includes many extreme physical phenomena and variability of different solid surface properties. In the present work, the cavitation bubble collapse in hydrophobic concave is studied using the pseudopotential multi-relaxation-time lattice Boltzmann model (MRT-LB). The model is modified by involving the piecewise linear equation of state and improved forcing scheme. The fluid-solid interaction in the model is employed to adjust the wettability of solid surface. Moreover, the validity of the model is verified by comparison with experimental results and grid-independence verification. Finally, the cavitation bubble collapse in a hydrophobic concave is studied by investigating density field, pressure field, collapse time, and jet velocity. The superimposed effect of the surface hydrophobicity and concave geometry is analyzed and explained in the framework of the pseudopotential LBM. The study shows that the hydrophobic concave can enhance cavitation effect by decreasing cavitation threshold, accelerating collapse and increasing jet velocity.