Second-Order Fields near a Pulsating Source

Abstract

An approximately spherical sound field of finite extent is produced in a liquid by a pulsating gas bubble. Observations of tracer particles near the bubble indicate an absence of acoustic streaming (as befits a spherical field) but the presence of radiation pressure. By the use of spherical tracer particles of different densities and compressibilities, comparisons with radiation-pressure theory can be made. At higher sonic amplitudes surface waves appear on the bubble accompanied by acoustic streaming in the nearby liquid. Measurements of the critical amplitude for the onset of these surface waves permit comparison with theory and with Eisenmenger's experimental results for parametrically excited plane surface waves. [This work was supported in part by a grant from the National Institutes of Health, Department of Health, Education, and Welfare.]