The Division of Fluid Dynamics of the American Physical Society sent out a press release about a new study a couple of their members recently published on cavitation, which is a word you’ll understand better from the description.

An old, hilarious if somewhat juvenile party trick involves covertly tapping the top of someone’s newly opened beer bottle and standing back as the suds foam out onto the floor. Now researchers from Carlos III University and Universite Pierre et Marie Curie, Institut Jean le Rond d’Alembert, have produced new insight into the science behind the foaming, exploring the phenomenon of cavitation.

Take a look at the release, The Physics of Beer Tapping Fluid Dynamics Explains Why Bottled Beer Bubbles Over When Tapped, and thanks to regular reader Russ R. for sending me the link. I like this explanation a bit better, though.

“Buoyancy leads to the formation of plumes full of bubbles, whose shape resembles very much the mushrooms seen after powerful explosions,” Rodriguez-Rodriguez explained. “And here is what really makes the formation of foam so explosive: the larger the bubbles get, the faster they rise, and the other way around.” He adds that this is because fast-moving bubbles entrain more carbonic gas.

Honestly, I don’t think I’ve ever done that to a person’s bottle. Of course, I tend to be around people who pour their bottle of beer into a glass.

Photo: Javier Rodriguez-Rodriguez / Carlos III University of Madrid, SPAIN Almudena Casado-Chacon / Carlos III University of Madrid, SPAIN Daniel Fuster / CNRS (UMR 7190), Université Pierre et Marie Curie, Institut Jean le Rond d’Alembert, FRANCE