Acoustic streaming field structure: The influence of the radiator

Abstract

In this paper the general structure of acoustically driven flow is considered, with particular emphasis on the acoustic radiator and its influence on the flow. The exact statement of the boundary condition at the face of the acoustic radiator is included in the usual perturbation approach to streaming theory. The result is a mathematical system that incorporates the influence of the radiator in its description of streaming flow. It is found that flow is driven at the face of the radiator by a streaming mechanism that has not been investigated before. This ‘‘boundary-drive’’ mechanism and the other, well-known streaming mechanisms are each characterized in terms of physical origin and the qualitative features of the resultant flow.