Liquid Polyhedra
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
2 comments:
Well, I don't really understand it, but it's beautiful!
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.
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