Quasi acoustic streaming induced by generation of cavitation bubbles

Bulk fluid movement induced by the generation of acoustic cavitation bubbles is discussed using experimental results from laser Doppler velocimetry. In contrast to the ordinary acoustic streaming generated through absorption of ultrasound, which is apparent at higher frequencies, bubble-induced acoustic streaming comes from the direct action of acoustic radiation pressure on cavitation bubbles and is observed even at lower frequencies. The fluid motion is intermittent, corresponding to the generation of bubbles followed by an exponential decay in velocity. Since the generation mechanism is quite different from the ordinary one, this should be termed quasi acoustic streaming