Originally published at: https://boingboing.net/2020/10/28/liquids-get-mixed-then-unmixed-due-to-stokes-flow.html
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Woah …
Seriously, who needs ESP when you’ve got genuine certifiable weirdness like that going on?
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Very cool demonstration. The camera angle was fixed from the side, so the overlapping colors could give the appearance of mixing even if they didn’t contact each other. I would be curious to see what this looks like from above, and whether the droplets were at different radial distances from the center of the apparatus. If viewed from above would it look like the droplets stretched into several distinct concentric circles?
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Totes Stokes flow bro.
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Wait, there’s more:
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Laminar flow is a real problem in heat exchangers when trying to heat / cool fluids. That’s why static mixers are often employed inside the tubing to make sure the flow is interrupted along the length of the tubing.
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This guy learned about the reversibility of swirling the hard way: he posted swirled photographs of himself online committing awful acts of child molestation, and someone was able to de-swirl his face and he was promptly identified and arrested. Hooray for reversing laminar flow/Stokes flow/whatever it is.
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This apparatus allows for the visual examination of a fluid undergoing laminar flow
Whilst technically and scientifically correct, the word ‘fluid’ here is not being used in an everyday sort of way. Nor ‘flow’.
Seeing the initial drops just hang there, frozen, was a bit of a clue.
Still pretty darn cool, though.
And people say you can’t unpiss in the pool
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control z
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Mind blown. I dont understand how this isn’t unscrambling an egg, even if they didn’t mix.
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This is the experiment that inspired physicist David Bohm’s theory of implicate and explicate order.
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I’d say “fluid” here fits the non-scientific definition too. The drops hang there because they have the same density as liquid they are suspended in, and the viscosity is high. For example Automatic Transmission Fluid is very viscous compared to water, but it is also called fluid in everyday language.
Perhaps sadly, automatic transmission fluid is not part of my everyday experience or language. 
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It’s a more popular term in rural places, especially among people who repair their own cars (automatic transmission fluid) and tractors(hydraulic fluid - also very viscous, similar to ATF). It’s kinda fun to service your own machines, but it can get messy and frustrating.
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