ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

5aPAb13. A study of the natural frequencies of spherical and distorted bubbles in open cavities.

Andrea Prosperetti

Hasan N. Oguz

Jun Zeng

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

The natural frequency of a bubble in an open, liquid-filled cavity is studied. A number of axisymmetric and three-dimensional configurations are considered such as a bubble in a cylindrical tube closed or open at one end and open at the other, a bubble between two parallel plates, a bubble in an open spherical cavity, and others. For bubbles that are smaller than the acoustic wavelength, the incompressible potential flow approximation is adequate. The natural frequency is computed by a boundary integral method. A slightly overexpanded bubble is allowed to relax and oscillate, and its frequency is measured by taking the Fourier transform of the volume pulsations. Alternately, a constant potential over the bubble surface is imposed and the natural frequency is calculated from the resulting volume flow rate of the bubble. These two techniques give nearly identical results for linear oscillations. For each geometry, spherical as well as distorted bubbles are investigated. [Work supported by the Office of Naval Research.]