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by aaren
4617 days ago
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The 'Rankine vortex' is a simple model for a vortex in which the centre is in solid body rotation and the rest is a free, irrotational* vortex. From the looks of their video, the bottle forms most of the solid body core. The velocity in the rest of the fluid goes as u~1/r and is pure tangential (streamlines are circles around the vortex centre). This isn't anything special, it's just a pretty regular unforced vortex. *irrotational here means that the vorticity (defined at a point) is zero, not that the system doesn't look spinny. |
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