The acoustic signature of bubbles fragmenting in sheared flow

Measurements of the sound of bubbles fragmenting in fluid shear are presented and analyzed. The frequency, amplitude, and decay rate of the acoustic emissions from 1.8-mm-radius bubbles fragmenting between opposed fluid jets have been determined. A broad band of frequencies (1.8 to 30 kHz) is observed with peak pressure amplitudes in the range of 0.03 to 2 Pa. While the peak pressure amplitudes show no significant scaling with frequency, the frequency dependence of the decay rates is consistent with the sum of thermal and acoustic radiation losses. (c) 2006 Acoustical Society of America.