ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2pAO3. A theoretical study of natural frequencies of bubbles in sediments.

Andrea Prosperetti

Hasan N. Oguz

Dept. of Mech. Eng., Johns Hopkins Univ., Baltimore, MD 21218

Bubbles that are highly efficient scatterers have dramatic effects on the acoustic characteristics of sediments. The incorporation of such effects in continuum models requires the knowledge of individual bubble frequency and response to acoustic waves. For bubbles that are smaller than the acoustic wavelength but large enough that the liquid viscosity is insignificant, the potential flow approximation is reasonable. The natural frequency of bubbles surrounded by sediment grains of comparable size are computed by a boundary integral formulation allowing in detail for bubble deformation and the presence of rigid boundaries. Even though the geometry is restricted to axisymmetric cases, main features of this process are adequately captured by simulating a number of cases. Several configurations are tested and, in many instances, substantial differences between the current calculations and the commonly used formula have been found. [Work supported by the Office of Naval Research.]