The acoustically-driven expansion and collapse of a near wall bubble.

A high-order accurate, fully compressible, multiphase model is used to simulate the acoustically-driven expansion and collapse of a gas bubble in water. The Rayleigh collapse has been the standard model of collapse: it uses initially static distributions of pressures for which the pressures in the two domains are unequal and uniform. The model presented here initiates the bubble dynamics and the surrounding fluid dynamics by an oscillating moving boundary condition. The results of the acoustically induced collapse are compared to those of the Rayleigh growth and collapse. A small standoff distance greatly restricts the sphericity during the bubble's expansion stage. For similar maximum bubble volumes, the acoustical-driven collapse predicts much higher wall pressures than the Rayleigh model.