Vortex dynamics in an oscillating falling drop dripped from a faucet

The oscillations of a falling drop dripped from a faucet is investigated through experiment and direct numerical simulation. In the present study we consider the whole process of drop growth, detachment and oscillation. Excellent agreement between numerical and experimental results is achieved. The development of the drop before pinch-off is found to be well predicted by the theory of static pendant droplet. The influence of pinching to the high-order mode oscillations is investigated. The temporal evolution and spectra of the drop top and bottom radii show that Rayleigh's theory is valid in predicting the frequencies of high order modes. The interplay between capillary oscillation and the external flow induces a complex unsteady flow that is fundamentally different from the classic circulation in the form of Hill's vortex. The vortex dynamics and the resulting chaotic mixing within the drop are investigated by swirling strength (λci) criterion.