Analysis of Acoustic Streaming by Perturbation Methods

Abstract

Streaming is an interesting phenomenon that arises due the nonlinear behaviour of fluids undergoing oscillations. The nonzero mean flow that takes place in the background of the oscillatory flow is referred to as streaming. We have presented here perturbation techniques that can be employed to understand the detailed fluid dynamics for systems where streaming happens, and our focus is on the Schlichting-type streaming that takes place when an oscillating fluid interacts with a solid surface where vorticity is generated and nonlinearities set in. It has been demonstrated that this type of streaming can also occur due to interaction at fluid–fluid interfaces. This chapter is dedicated to perturbation methods whereby analytical solutions can be developed for the nonlinear problems when a set of small parameters can be identified. The discussion deals with some one- and two-dimensional cases followed by three-dimensional axisymmetric situations involving spherical particles, drops and bubbles.