Bar Trick Reveals Better Understanding Of Fluid Dynamics

beer foamWithout fail someone always taps my friend Susan's beer bottle and makes it overflow. She gets so mad and makes an attempt to salvage the overflowing beer. This started many moons ago but the tradition continues because of her reaction. Aside from being wasteful, it's funny.

Who knew that researchers are doing a high-tech tap of the beer bottle in the name of science? According to a press release from the Institution of Chemical Engineers (IChemE), they use a high-energy laser to create a bubble at the bottom of a newly opened bottle of beer then hit its neck. A high-speed camera, recording at 50,000 stills per second, found that the process had three distinct phases.

A vertical hit causes a shockwave that generates expansion and compression waves. When these reach the bottom of the bottle, the bubbles there burst into smaller bubbles, creating small balls of foam. These weigh much less than the surrounding beer and rise so rapidly to the top of the bottle that the result is similar to an explosion. In less than one second, virtually all the beer can be made to shoot out of the bottle.

This cavitation effect is similar to the effect in a mushroom cloud caused by a nuclear explosion, and occurs in part because there is more carbon dioxide (CO2) in the solution than it can maintain. Usually it would escape slowly, but a knock sets off a chain reaction that causes the gas to erupt.

While I say that any research involving beer is good research, some may wonder why money is being spent on this study. The answer comes from lead researcher Javier Rodríguez, a thermal and fluid dynamics professor at Universidad Carlos III de Madrid. He says the knowledge could help predict the volume of gases that might erupt as a result of volcanic activity – such as in the 1986 Lake Nyos disaster in Cameroon, in which 1,700 people were suffocated by CO2.

Andy Furlong, director of policy and communication at IChemE, says: “This research will be of wide interest including to chemical engineers who are the specialists behind the large scale brewing and bottling of famous household beer brands across the world.

“This greater understanding of fluid dynamics is always valuable especially when one considers the scale and complexity of modern brewing and bottling plants, and the forces and pressures involved during the manufacturing process."

I think it's high time I call Susan and invite her out for a beer. We'll catch up on old times and discuss Rodríguez' research and I will be sure to offer a demonstration in fluid dynamics.

Read the release from IChemE.

Traci-bio-photo.jpgTraci Purdum
Senior Digital Editor and beer prankster