The Aerodynamics of Foam

Here’s an interesting, and perhaps counter-intuitive result. Everyone knows that it’s the flow of air over an airplane’s wings that provides the lift that keeps the plane aloft. But what if you replace the moving air with foam? Some French physicists found that in that case the resulting force is exerted downwards rather than upwards. They call this “anti-inertial lift,” and say it could have implications in all kinds of fields: oil extraction, industrial cleaning processes; and it “might even shed light on how embryonic cells rearrange themselves in a growing foetus.”

The paper’s abstract, from Physical Review Letters, is here.