Oscillation of liquid drops under gravity: influence of shape on the resonance frequency

A recently demonstrated technique of aerodynamic levitation has been used to study the resonance frequency of liquid droplets. A thin pressurized gas layer supports the droplet avoiding any contact with the environment. Due to the external gravitational field, the measured frequency is different from the one predicted by the classical models for a spherical drop. An ellipsoidal shape has been introduced to take into account the competition between surface and gravitational energies. Results of this model are in good agreement with experiments in terms of volume, as well as density and surface energy, dependence of the oscillation frequency.