The motion of bubbles in a sinusoidally oscillating liquid in microgravity

Abstract

The sinusoidal motion of single, spherical bubbles in microgravity was studied experimentally aboard the U.S. Space Shuttle. Tests were performed to determine the effect of frequency, acceleration amplitude, bubble size, and fluid viscosity on bubble motion. Five test cells each containing a single bubble were subjected to rectilinear, sinusoidal oscillations. Three nominal bubble sizes and three liquids were used to cover a range of Stokes numbers from 1.3 to 21 and Reynolds numbers from 0.6 to 75. Bubble motion was recorded by video. The ratio of bubble motion amplitude to container motion amplitude was found to be essentially independent of the actual container motion amplitude. Therefore, this ratio could be plotted against frequency to obtain a frequency response for each case. This ratio was found to rise sharply from zero at zero frequency and then approach an asymptote at high frequencies. The strong effect of the walls in these experiments caused the amplitude of bubble motion to be reduced somewhat from that expected for an infinite fluid.