GROWTH OF BUBBLES BY RECTIFIED DIFFUSION

A bubble that would ordinarily dissolve in a liquid may instead grow by a process known as rectified diffusion, if it is located in a sound field of sufficient pressure amplitude. Threshold conditions for bubble growth and the rate of bubble growth have been measured for air bubbles in air saturated water at an acoustic frequency of 26.6 kHz. The experimental results are compared to newly calculated results based on a theory of rectified diffusion by Eller and Flynn [J. Acoust. Soc. Amer. 37, 493 503 (1965)]. The results refer to bubble radii from 15 to 90 μ and pressure amplitudes of less than 0.3 bar. For these conditions, it is found that the experimental and theoretical rectified diffusion thresholds show rough agreement, but the measured rates of growth, for pressure amplitudes above the threshold, can be much greater than the calculated rates of growth. © 1969, Acoustical Society of America. All rights reserved.