Sloshing Resonance of Acoustically Levitated Air-in-Liquid Compound Drops

An acoustically levitated liquid droplet containing an air pocket is driven into an out-of-phase azimuthal 'sloshing' resonance by a frequency modulation with modes n = 4 to 9. The inner and outer liquid-air interface waveforms are consistent with the standard Saffren model. The frequency spectrum resonance peaks and their harmonics are found to be a function of droplet size and resonance modes. Due to asymmetry, droplets with several tiny air pockets do not resonate in time with the cavitation. This research has major implications for the dynamics of cavitating drops.