Acoustic streaming produced by sharp-edge structures in microfluidic devices

The effect of acoustic streaming produced by sharp-edge structures is used in a variety of microfluidic applications, such as fluid mixing, pumping and particle manipulation. Since most investigations into this effect are experimental, there is a necessity in theoretical studies that could provide a deeper insight into the mechanism of the acoustic streaming and point out ways for optimizing acoustofluidic sharp-edge-based devices. In the present study, an analytical theory is developed that allows one to evaluate the velocity field of acoustic streaming generated at the apex of a wedge-shaped structure. Streamline patterns calculated by the developed theory show that the acoustic streaming is formed by two counterrotating vortices at the wedge apex. In addition to the analytical model, a numerical model is realized using the finite element method. Predictions of both models are described and compared with experimental observations.