Studying the flow of soap film has been thought to be a convenient way to study 2-D turbulence in a search for answers to geophysical systems. But research with such models has been inconclusive, largely because methods have enabled only single-point velocity measurements.
Researchers at Los Alamos National Laboratory in New Mexico, reporting in Physical Review Letters (Aug. 17, 1998, pp. 1417-1420), have devised a method that measures velocity at thousands of points in a cascade of soap film. The technique measures velocity, vorticity and film thickness simultaneously. Despite some minor concerns, preliminary results confirm the validity of 2-D turbulence studies.
The digital particle-image velo- cimetry system is based on a soap film tunnel, in which a comb is inserted to create turbulence. A CCD camera with 1008 x 1008-pixel resolution images the flow, while 0.36-J, 3-µs bursts of light from xenon flashlamps provide illumination. Adding titanium dioxide to the mixture makes the film's eddies visible.