These guys used a bowl of washing up liquid to generate a soap film some 10cm across in a wire frame. They then pumped a stream of soapy water through a sub-millimetre nozzle to create a jet with a size and velocity they could vary.  Finally, they fired the jet at the film at various different angles to see what happens. It turns out that the film is surprisingly robust. “Regardless of its velocity, radius and incident angle, the jet never breaks the soap film,” say Kirstetter and co. But something else happens instead: the film bends the jet by an amount that depends on its angle of incidence. In effect, the film acts like a lens, and Kirstetter and co are able to derive a kind of Snell-like law to describe this kind of refraction.

When a Jet Hits a Soap Film | MIT Technology Review Saturday, February 15, 2014 @ 3:57pm