Acoustic streaming is the formation of a steady fluid motion promoting agitation and mixing in the liquid.
Acoustic streaming generated from a 20 kHz source was experimentally measured using Particle Image Velocimetry (PIV) and numerically predicted in water. The numerical model was subsequently applied to liquid aluminium considering the effect of cavitating bubbles for the first time. Results showed that volume bubble fraction and sonication power regulates the upward or downward flow of the acoustic streaming.
The occurrence of either upward or downward centreline flow by model and experiment according to sonotrode power may introduce additional useful flexibility on how ultrasonic processing may be applied to liquid metal processing during casting, and in other sono-technologies.