Fluid Mechanics of Gas Jets and Vortex Rings Released from Bursting Bubbles

Bubble bursting is important in ocean-atmosphere processes (e.g. marine aerosol formation), food science (e.g. champagne), and industrial processes (e.g. gas fluxing of molten metal to remove impurities). The fluid mechanics of the liquid component of bubble bursting, including film cap retraction and droplet formation, has been well studied. In contrast, the fluid mechanics of the pressurized gas released from a bursting bubble has not been well investigated, but this flow may influence the mixing of released gas and the spatial distribution of generated droplets. Here we investigate the gas flow released from the bursting of smoke-filled bubbles floating at an air-liquid interface using high speed visualization at 10 kHz. For air-water bubbles of 3.5 cm diameter, the ruptured bubble cap releases a jet with a speed of 4.6 m/s through the expanding hole in the bubble film. The jet rolls up into a vortex ring which may travel tens of bubble diameters. Jet speed decreases linearly with size to approximately 1.6 m/s for an 0.5 mm diameter bubble. Jet speed decreases for similarly sized bubbles in more viscous liquids. Using dimensional analysis, we compare the effects of surface tension, viscosity, and bubble size on gas jet speed and vortex ring characteristics for various liquids.