Internal flow of acoustically levitated drops undergoing sectorial oscillations

We present the experimental observation and theoretical analysis of fluid flow in acoustically levitated water drop undergoing sectorial oscillations. The fluid always flows between the extended sections and the compressed sections. The magnitude of fluid velocity decreases from the equatorial fringe to the centre of levitated drop. The maximum fluid velocity is 60–160 mm/s and the Reynolds number of the oscillations is estimated to be 137–367. The internal flow of the drop is analyzed as potential flow, and the fluid velocity is found to be horizontal. In the equatorial plane, the calculated stream lines and velocity profiles agree well with the experimental observations.