Shock-bubble interaction near a rigid surface

Michael L. Calvisi
School of Mathematics, The University of Birmingham

*Jonathan I. Iloreta
Department of Mechanical Engineering, University of California at Berkeley

*John R. Blake
School of Mathematics, The University of Birmingham

*Andrew J. Szeri
Department of Mechanical Engineering, University of California at Berkeley

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     Last modified: February 23, 2007
     Presentation date: 06/13/2007 10:50 AM in ITU Macka Conference Room
     (View Schedule)

Abstract
In this talk, we present the results of numerical simulations of the nonspherical collapse of bubbles excited by shock waves near a rigid boundary. The waves we consider are representative of those developed by shock wave lithotripsy or shock wave therapy devices. The rigid boundaries we consider are representative of kidney stones and reflective bony tissue. The presence of the boundary causes constructive interference between reflected and incident waves that enhances the expansion and subsequent collapse of bubbles located in a region near the boundary. Quantities such as kinetic energy, Kelvin impulse, and centroid translation are calculated in order to illuminate the physics of the collapse. The main finding is that the dynamics of the bubble collapse depend strongly on the distance of the bubble relative to the wall when reflection is taken into account but much less so when reflection is omitted. The work done by the shock wave on the bubble is shown to predict strongly the maximum bubble volume regardless of the standoff distance and the presence or absence of reflection; furthermore, with appropriate interpretation, these predictions match almost exactly those of a spherical bubble model.