Dynamics of two interacting acoustic bubbles at short separation distances

Abstract

We investigate experimentally the attraction between two closely spaced, oscillating microbubbles. Above a certain value of the applied acoustic field, the bubbles jump to a new equilibrium location, where they are separated by a thin fluid layer whose the thickness is much smaller than the bubble radii. We demonstrate that this new equilibrium is caused by the sign reversal of the radiation interaction force acting between the two bubbles, attributed to the multiple rescattering effects of the waves emitted by the bubbles. Theoretical investigation reveals that a new stable equilibrium appears at short distances, resulting in a quasi-contacting bubble pair.