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A bubbly toast to researchers

By Shelley Widhalm
January 3, 2008

Mostafa Shakeri (left) and Mohammadreza Tavakolinejad work with their wave-simulation equipment at the University of Maryland at College Park. They use a laser beam and shadow graphs to track the bubbles in waves.

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Revelers opening bottles of champagne to ring in the new year unwittingly got a glimpse of the beach. The bubbles that rise up and swirl around a champagne flute are similar in one way to the bubbles created by breaking waves.

A graduate research team at the University of Maryland in College Park is studying bubble phenomena in breaking waves. Although they are not considering champagne bubbles, the behavior of the bubbly imbues their experiment, which is in its sixth year, with a holiday interpretation.

"You need to have patience when you do such an experiment. It takes a long time to get results," says Mostafa Shakeri, a postdoctoral student with a doctorate in mechanical engineering.

Bubbles are pressurized, thin-walled spheres of liquid containing air or gas that are ready to collapse. The bubbles in champagne and some of those from breaking waves contain carbon dioxide.

In the case of champagne, popping the cork lowers the pressure in the bottle, causing the carbon dioxide in the liquid to no longer be in equilibrium, says James H. Duncan, professor of mechanical engineering at the university.

"It can be at a certain pressure and temperature, but if it's less, then the carbon dioxide has to come out. It's called saturation. There's a saturation quantity in liquid for each temperature and pressure," says Mr. Duncan, who holds a doctorate in geophysical fluid dynamics.

The carbon dioxide is released from the liquid in the form of bubbles, Mr. Duncan says. Bubbles also form when champagne is poured into a flute where there are nucleation sites, such as imperfections in the glass and dirt, dust and fiber particles, he says.

Alternatively, bubbles occur in ocean waves when the surface of water is folded over, such as by a breaking wave, Mr. Duncan says. As the wave curls over, it traps air, which consists of nitrogen, oxygen and other gases, including carbon dioxide, he says.

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