Chaotic mixing in an acoustically driven cavity flow

In this numerical study, we investigate the mixing properties of an acoustic driven flow in a parallelepipedic cavity with square basis in view of applications in photovoltaic crystal growth configurations. A single acoustic source is used, but, relying on non-normal reflections, an acoustic beam with a square path is obtained, generating a global complex flow in the cavity. Depending on the power of the source, the flow field may be steady, periodic in time, or chaotic. We restrict here on the steady and periodic cases and show that those flow fields enable chaotic advection. In the case of oscillating periodic flow fields, the chaotic region invades the whole cavity, as shown by numerical simulations of Poincar?? sections and animations of mixing. This illustrates that acoustic streaming at moderate powers can be used successfully as a nonintrusive tool to mix efficiently.