Love it or leave it, the foamy head on a vigorously poured pint of beer does a lot more to benefit the sensation of your libation than you might realize. Beer foam—a latticework of carbon dioxide gas bubbles trapped in a matrix of grain proteins, hop alpha acids, metal ions, and beer itself—is a fantastic visual and aromatic indicator of the type and quality of the potent potable poured into the pint put in front of you. In addition to the pleasant sight and smell that beer foam provides, it also helps to present the full range of the beer’s flavor profile, “softens” the palate, and provides a carbonated tingle to the tongue upon quaffing. But as a new physics study shows, a healthy layer of foam will actually help to keep more of the liquid gold in your glass rather than sloshing over the rim.
A new paper published in the Physics of Fluids journal (via Gizmodo) set out to investigate the effects a foamy layer has on the liquid below it when it comes to oscillations, i.e. sloshing. Their findings revealed that the foam layer dampens oscillations in the liquid layer much more quickly than the traditional thinking could explain.
Conventional wisdom says that any liquid sloshing back and forth in a container will dissipate energy as it does so, resulting in each oscillation getting smaller and smaller. However, this explanation suggests that the oscillations will dampen exponentially, but will never stop. The new study puts a foamy damper on this idea thanks to capillary action. This phenomenon, one that explains how trees move liquid from their roots to their great heights or how some insects walk on water, results from forces due to surface tension.
“Those capillary forces are small, but they’re very important as soon as the sizes or motions get small,” said Pierre-Thomas Brun, a mathematician at the Massachusetts Institute of Technology and co-author on the paper. These capillary effects from innumerable little bubbles “induce tiny pressure gradients near the walls of the container, which drives small motions in the liquid that reduce the sloshing.” To make things a bit stranger, the slower the velocity of the oscillation becomes, the quicker it dissipates, resulting in much less sloshing in a relatively short time. These findings have real-world implications that range from better control and stability of oil in transport tankers and liquid fuel in rocket tanks, to keeping the better part of your beer within your glass.
Learn a little more about brewing beer and the benefits of beer foam thanks to UC Davis’ Charlie “Pope of Foam” Bamforth:
Do you appreciate a good head on a pint of beer for any other reasons than the ones mentioned above? Let us know in the comments! Cheers!
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Images: Been Around/Flickr