Collective oscillations in a bubble column: Higher modes

Abstract

One possible source of ambient noise in the ocean is clouds of bubbles generated by a variety of mechanisms at the sea surface and extending down to depths of several meters [A. Prosperetti, J. Acoust. Soc. Am. 83, 1042–1054 (1988)]. Experimental evidence exists [Yoon et al., J. Acoust. Soc. Am. (1990)] that demonstrates that the sound generated by a cloud of bubbles is characteristic of the gross features of the cloud itself. From the analysis of underwater acoustic emissions of these “collective oscillations,” the numerous modes of vibration of a column of bubbles were studied, including a variety of boundary conditions, and these results compared against theoretical predictions. Because of the excellent agreement that exists between predicted and measured acoustic characteristics of the bubble‐filled column, it appears that the theory for describing such collective oscillations is becoming firmly established. [Work supported by ONR and ONT.]