Fizzy physics

When bubbles burst at a liquid’s surface, as seen in champagne or carbonated drinks, droplets are ejected. This little event, which is commonly seen in much greater scale on the ocean’s surface, involves a fascinating facet of physics.

When bubbles burst, the thin liquid film at the surface, the ‘bubble cap’ that separates the bubble from the atmosphere, disintegrates and the resulting opened cavity collapses. This, in turn, causes an upward jet that releases a few tiny droplets as it breaks up.

Researchers working at the Institut d’Alembert, in France, have described the intricate roles of bubble shape, capillary waves, gravity and liquid properties in bubble-bursting jet dynamics.

The researchers demonstrated that droplet ejection depends not only on the bubble geometry, but also, critically, on the liquid properties. Unexpectedly, they found that bubbles bursting in more viscous liquids produce smaller and faster droplets.

These results should help pave the road to the control of bubble-bursting aerosols and may find more novel applications in aroma diffusion in champagne or wine. “By changing the viscosity of champagne slightly, we could generate an aerosols-optimising-the-diffusion aroma,” researcher Thomas Seon noted.