Dynamics of bubbles near a rigid surface subjected to a lithotripter shock wave. Part 1. Consequences of interference between incident and reflected waves

In this paper we consider the dynamics of bubbles near a kidney stone subjected to a lithotripter shock wave. We address the effect of kidney stone geometry and composition on the cavitation potential near the stone in a shock wave lithotripter. The analysis is based on the previously developed work metric in which the work done on a bubble by the lithotripter shock wave (LSW) is used to determine the maximum radius the bubble achieves. Results of the reflection of the LSW from cylindrical kidney stones with proximal surfaces of varying geometry show that the presence of the stone enhances bubble growth near the stone and decreases growth further away, owing to constructive and destructive interference, respectively. These effects hold true regardless of the shape and curvature of the face, and are strongest for stones with concave faces and higher reflection coefficients. A consequence of the analysis is an elucidation of the mechanism for enhanced cavitation activity and creation of deep craters on the proximal side of a kidney stone, as have been observed in recent experiments.