There are drawbacks to creating turbulence in films by touching them. For one, you create large variations in thickness which are at time undesirable. We investigated a technique where we hold metal strips close to the film. This slows the film down locally, which makes it only slightly thicker. The following image shows the film with metal strips behind it.
We can place more strips on the front, so the film rushes through a gap only a few millimeters wide. At this point the flow difference along the strips is strong enough to make the flow unstable. You can see the result of a coarser set of metal strips on the right hand side of the next image.
This relates to flows on the surface of Jupiter. You have probably all seen photos such as this one:
You may not have realized that the bands of different color are moving rapidly in opposite directions. This you can see nicely in this time lapse movie from nix.nasa.gov.
Quicktime Movie |
The same physics which drives Jupiter's atmosphere turbulent drives can drive our soap films turbulent.
Soap film images copyright (2000) Maarten Rutgers and Brent Daniel.
Jupiter images courtesy of NASA.