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Slosh-stopping Foam

February 26, 2015

Engineers discover what waiters and bartenders have known for centuries: foam keeps drinks from sloshing.



Café-inspired sloshing solutions.  I’m Bob Hirshon and this is Science Update.

What do beer and cappuccino have in common? Foam, of course. And according to engineer Emilie Dressaire, at the New York University Polytechnic School of Engineering, both drinks slosh less than their foamless counterparts.

EMILIE DRESSAIRE (New York University Polytechnic School of Engineering):

The interesting thing about foam is it’s composed of a collection of small bubbles, and between those bubbles you’ve got thin layers of liquid. And when those layers of liquid tend to move along the walls of your cup, that creates the damping that we’re talking about here, we’re decreasing the amount of sloshing.


She says sloshing isn’t just a problem for waiters—many industries transport containers of liquids, and sloshing can destabilize the ship, train or truck that carries them. She and her colleagues are now studying what sorts of foams might be best at subduing the sloshing in different liquid products. I’m Bob Hirshon, for AAAS, the science society.