Marangoni vortex rings in miscible spreading

This work investigates the dynamics of a unique, radially expanding vortex ring in a water layer when a miscible, volatile drop of ethanol spreads as a film on the air-water interface. The study unravels the link between the dynamics at the interface and the generation of vorticity in the water layer below it. A novel scaling is proposed for the radius and velocity of such vortex rings, where they are shown to be dependent on time as well as the properties of the drop and the substrate.