Research on the collapse dynamics of a restricted cavitation bubble near a right-angle wall based on Kelvin impulse theory

Abstract

In this paper, a Kelvin impulse theory model is constructed for a restricted bubble through conformal transformation. The collapse dynamics of a restricted bubble near a right-angle wall are systematically investigated based on the result of the new theoretical model and a high-speed photography experiment. In particular, the bubble collapse jet, characterized by the intensity and angle of the Kelvin impulse, is visualized and analyzed with experiment validations. The corresponding results for an unrestricted spherical bubble are also investigated for comparison purposes. The pivotal conclusions are as follows: (1) The Kelvin impulse intensity takes its maximum value at the position where the bubble is closest to the vertex of the right-angle wall. Furthermore, the intensity decreases with an increase in the dimensionless distance, and first decreases and then increases with an increase in the bubble azimuth angle. (2) The rates of change of the Kelvin impulse intensity and direction of the bubble are both very sensitive to the bubble position when the bubble is near one of the straight walls of the right-angle wall. (3) The trends of both the Kelvin impulse intensity and direction with the bubble position for restricted and unrestricted bubbles differ significantly because of the different characteristics of the Bjerknes force for the two kinds of bubbles.