Abstract:

Bubble cloud resonances have been proposed as an explanation of the low-frequency acoustic radiation produced by breaking waves. A previous model [H. N. Oguz, J. Acoust. Soc. Am. 95, 1895--1912 (1994)] considered excitation of the bubble cloud by a rigid piston at the base of a hemispherical bubble cloud. The present model considers excitation of the cloud by individual points sources within the cloud. A Green's function is obtained for a point source displaced from the origin of a hemispherical bubble cloud beneath a pressure release surface. The radiation pattern for multiple point sources distributed within a slice of the hemispherical cloud is obtained by superposition and the method of images. The effects of bubble cloud characteristics on the radiation field will be shown for various frequencies and ranges of point source depths. The method presented here is applicable to modeling sound generation of breaking waves having bubble clouds that are not amenable to being modeled by a hemispherical geometry. For instance, bubble clouds produced by breaking surf might be modeled more accurately using a cylindrical bubble cloud geometry. [Work supported by ONR.]