Acoustic Streaming at Low Reynolds Numbers

Abstract
This paper is a continuation of an analysis of acoustic streaming begun in a previous paper where streaming at high Reynolds numbers (order of several hundred) was treated. The corresponding problem for low Reynolds numbers (order of ten) is now considered, and it is shown that the flowpattern obtained around a cylinder in a sound field is opposite to the one corresponding to high Reynolds numbers. The Reynolds number is defined as R = U 0 a/v, where U 0 is the particle velocity in the incident sound wave, a is the radius of the cylinder, and v is the kinematicviscosity. The two types of flow associated with different values of Reynolds numbers seem to correspond to the two types of circulations that have been experimentally observed and reported in the literature.