Characterization of a large vortex using acoustic time-reversal mirrors

Abstract:

We report new results on the ultrasonic characterization of a fluid flow using an acoustic time-reversal mirror (TRM). The structure of a large vortex generated by a rotating disk in a hollow cylinder is investigated both inside and below the cylinder. For mean-flow characterization, the TRM is shown to be a powerful vorticity detector. Experimental time-of-flight data are successfully compared to a numerical simulation of the flow and the orthoradial velocity is reconstructed using simple geometrical acoustics. Real-time measurements allow us to extract the precession motion of the vortex, providing direct, non-intrusive, and dynamical information on the flow.