Kerry K. Kuehn

Flowing soap film movies

Below are a few movies of flowing soap films captured by my research assistants, Elise Sloey and Amelia Lauth. The soap film is falling downward between two vertically oriented fishing lines. It is illuminated with a mercury vapor lamp. Reflected light from the front and back surfaces of the film gives rise to the variously colored interference fringes which can be seen.

The first clip shows a static fringe pattern due to time independent-flow during the first minute or so. The flow is then turned off, and the pattern becomes time-dependent as surface-tension gives rise to swirling flow patterns. In the second clip, a small cylindrical tube is inserted into the falling film. This gives rise to a clearly discernible wake structure. More still images can be seen here.