THE MECHANISM OF GENERATION OF ACOUSTIC STREAMING

Acoustic streaming is a stationary fluid motion induced by intense ult rasound. This paper describes the mechanism of generation of acoustic streaming, theoretically and experimentally. A qualitative explanation in relation to acoustic radiation pressure is followed by a detailed discussion based on the formulation of the phenomenon. The spatial non -uniformity of the sound field and energy dissipation due to viscosity are requisite for the generation of streaming. In the development of streaming, two kinds of nonlinearity are important: one is fluid-dynam ic nonlinearity, which accounts for effects of inertial force compared to viscous force in fluid motion, and the other is acoustic nonlinear ity, which determines the driving force of streaming. (C) 1998 Scripta Technica, Electron Comm Jpn Pt 3, 81(10) : 1-8, 1998.