Harmonic resonance of acoustically levitated two-phase droplets

A droplet of a mixture of immiscible water and oil is levitated in a standing acoustic wave and is set into resonance.The in-situ recording of the resonating droplet allows one to determine the mode number (or number of equatorial lobes) at characteristic frequencies which depends on the fluid viscosity, surface tension, and droplet size.Since the mixture is immiscible, the surface wave is distinctly different from the pure liquid, and the resonance frequency falls in between the values of pure components.