Make these four classic cocktails and become a fluid dynamics expert

Gin Fizz

Proteins come together to make the foam in a gin fizz

Alex Overhiser

YOU may think that complex equations and alcohol don’t, or perhaps shouldn’t, mix. But make your favourite cocktail and you will unknowingly encounter some of the most complex processes in fluid dynamics, the study of how liquids flow.

When researchers try to predict how a fluid will move, bubble or create waves, they often run into complicated equations. The starting point for solving almost any of these problems is the Navier-Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes. The pair devised them in the 1800s, which also happens to have been the golden age of mixology.

What better way, then, to learn about fluid dynamics than by indulging in some cocktails? Whether it is how foams are made, the formation of unusual clouds or liquids spurting at supersonic speeds, some wonderful surprises can hide in a drink. Roll up your sleeves and dig out your cocktail shaker!

GIN FIZZ

Experience the miniature marvel of foams

First up, something fizzy. Made from two parts gin, one part lemon juice, a dash of syrup and a splash of soda water, the gin fizz would be simple were it not for its layer of foam.

Foams challenge physicists. At times, they behave like solids; at other times, they act like liquids. Soapy bubbles flow like water when you wash your dishes, but the stiff head of a beer can be sliced off in one.

This difference comes down to the bubbles. When bubbles crowd together, they make a foam. But how…