On the generation of vorticity and hydrodynamics of vortex ring during liquid drop impingement

In this work, we investigate the phenomenon of vortex generation and formation of a vortex ring when a liquid drop impinges on a miscible liquid surface. Although the formation of a vortex ring for this system has been studied for more than a century, little is known about its exact mechanism of generation and how its hydrodynamics is related to the shape of the drop. This is due to the complexity involved in the conversion of the initially generated vorticity into a vortex ring. To cast light on this intriguing phenomenon, time-resolved high-speed imaging with high magnification is used. This allows us to probe deeper into the vortex generation process and study the formation of the ring. We make a comprehensive study of the effect of drop impingement height and drop shape at the time of impact on the vortex generation and the hydrodynamics of the ring. The effect of crater evolution on the hydrodynamics of the vortex ring is studied in terms of its diameter and translational velocity. By examining the role of the shape of the crater on vortex ring penetration, we answer the question why the most penetrating vortex rings are generated by a prolate shaped drop.