Numerical Study of the Collapse of a Bubble Subjected to a Lithotripter Pulse

Abstract

In shock wave lithotripsy, the combined effect of focused shock waves and cavitation pulverizes kidney stones. Although cavitation has been shown to play an important role in the stone comminution process, the underlying mechanism has yet to be fully understood. The goal of the present study is to quantify the potential damage caused by the collapse of a single bubble near a solid surface. Using a high‐order accurate quasiconservative, shock‐ and interface‐capturing scheme [E. Johnsen and T. Colonius, J. Comput. Phys., in press (2006)], the response of an air bubble subjected to a lithotripter pulse is considered. In particular, quantities important in cavitation erosion, such as wall stresses and reentrant jet velocity, are measured as functions of the properties of the pulse (amplitude, wavelength) and the geometry of the problem (stand‐off distance from the wall, presence of neighboring bubbles). Preliminary two‐dimensional results for a ‘‘cylindrical bubble’’ show that a large water‐hammer pressure is measured along the wall. This pressure increases for smaller stand‐off distances and longer wavelengths. Further results for spherical bubbles will be presented at the meeting.