EQUILIBRIUM SHAPES OF ACOUSTICALLY LEVITATED LIQUID DROPS.

Abstract

The nonspherical distortion of a liquid drop under the action of gravity and an imposed standing acoustic wave in a rectangular resonator is calculated. The calculation is based on the Young-Laplace pressure jump at the boundary of the drop, and is performed by expanding the distorted shape in spherical harmonics. The relative distortion of the drop is proportional to the ratio of the acoustic-to-surface-tension forces and is axially symmetric for a vertical standing wave. The mode l equals 1 corresponds to translational motion of the drop as a whole and gives a condition for the equilibrium position that is consistent with an independent calculation for a sphere balanced between acoustic and gravitational forces.