Zero frequency shift of an oscillating-rotating liquid droplet

Free-decay oscillations and rotations of a levitated liquid droplet are simulated numerically, and the frequency shift of drop-shape oscillations is studied. It is shown for an oscillating-rotating liquid droplet that the oscillation frequency decreases as the amplitude of drop-shape oscillations increases, while it increases as the rotation rate increases. The pressure difference between the equator and the pole of the droplet is found to correspond to the frequency shift. It is also found that the relation between the amplitude and the rotation rate is linear both for zero frequency shift and for zero pressure difference.