Liquid Polyhedra

Thursday, February 08, 2007



When a vertical water jet strikes a circular horizontal impactor, the water is deflected into a horizontal sheet. At sufficiently high speeds, the flow results in a circular water sheet, whose radius is set by a balance between inertial and curvature forces. At lower speeds, the sheet sags significantly under the influence of gravity, and may close, giving rise to a water bell....
The circular fluid sheets are marked by an axisymmetry-breaking instability that results in polygonal structures

3 comments:

Syl said...

Well, I don't really understand it, but it's beautiful!

Knucklehead said...

We used to do something similar to this when we were kids. Mouthful 'o water, hands hard against the cheeks, target... Not as beautiful or scientific as these but the same principles at work.

chuck said...

The same effect can be obtained by putting a line of something like dish detergent along the top of a pan, then quickly tipping it. The line will break into several equally spaced streaks as it runs to the bottom. Same principle: the boundary is unstable at some wavelength and the amplitude of perturbations at that wavelength grow until the boundary breaks into streaks at equally spaced intervals. It's a resonance effect.