Small-Scale Acoustic Streaming Effects in Liquids

Abstract

Observations (with low power microscope) have been made on isolated bubbles, forming on an inner wall of a specially devised liquid container, during irradiation with 10 kc sound. In the immediate bubble neighborhood circulatory streaming motions can often be seen. These small scale motions are especially violent if the bubble is of resonant size (about 0.6 mm diameter). It can be demonstrated that certain effects of high-amplitude sound are directly due to such motions. Studies have also been made of the circulation which takes place when a small source of oscillatory flow is situated near a fixed boundary. The vortex pattern set up in this way has been compared with that generated by an oscillating bubble. Theoretical considerations will be presented.