(A) toroidal bubble crossing an interface between two immiscible liquids

Abstract

The dynamics of a vortex ring bubble passing through an oil-water interface are experimentally investigated. The vortex ring bubbles are generated by compressed air ejected through an orifice for a short duration of time. The volume of the vortex ring bubble is controlled via the pressure and ejection time of the pressurized air. As the vortex ring bubble passes through the horizontal interface, it entrains and transports the lower liquid. The bubble and the interface interactions show notable differences from the interaction between a single-phase vortex ring and a density interface. Throughout the upward motion of the vortex ring bubble, kinematic properties such as the radius and velocity of the bubble are primarily determined by the relative magnitude between the buoyancy and the gravitational forces acting on the vortex structure composed of the bubble and the entrained fluid. We investigate key dimensionless parameters that can characterize the dynamics of the interface.