Small-Scale Acoustic Streaming in Liquids

Abstract

By using special acoustical and optical arrangements, vortex motions are discovered in the vicinity of small vibrating sources in liquids. Of particular importance is the vigorous eddying that typically takes place near a vibrating gas bubble when it rests on a boundary. This bubble-associated streaming has been observed under a variety of circumstances, and apparently occurs quite generally. Especially violent and chaotic motions appear near bubbles of resonant size. The attendant highly localized convection and viscous stresses are probably very important as intermediate physical mechanisms for sonic irradiation effects.