Morphological characteristics and cleaning effects of collapsing cavitation bubble in fractal cracks

Abstract

When a cavitation bubble collapses in a crack, due to the lack of symmetry, spatial uniformity, and obvious correlations during the collapse process, it is difficult to effectively explore the interaction mechanism between the bubble and crack walls. In this paper, a combination of numerical simulation and experimental approaches are used to explore the collapse process of a cavitation bubble in a fractal crack. The numerical model is based on the pseudopotential multi-relaxation-time lattice Boltzmann method (LBM). The experiment platform including an underwater pulsed discharge device combined with a high-speed camera system. Moreover, the morphological analysis method based on Minkowski functionals is used to quantitatively depict the morphological features in this paper. The validity of the numerical model is qualitatively verified by the experimental platform, whereas the influence of the complexity and geometric features of the crack wall on the cavitation bubble collapse process is quantitatively studied by LBM simulation and Minkowski functionals. The research findings indicate that the complexity and geometric features of the crack wall markedly influence the collapse time and behavior of the cavitation bubble. Specifically, the collapse time of the cavitation bubble increases with the increasing complexity of the crack wall. Moreover, the maximum jet direction of cavitation bubble toward the wall is closest to the cavitation bubble. Furthermore, as the fractal dimension increases, the intensity of the pressure wave and jet acting upon the crack wall increase while the radiation range decreases. Cavitation cleaning can be applied to arbitrary complex solid surfaces in various environments.