Okay, technically this isn't a lava lamp, but you could have fooled me, given the mellow music and the drifting plumes of colored liquid. Researchers at Cambridge performed an experiment to find out more about fluid dynamics by coming up with two completely different ways that liquids can mix due to Rayleigh-Taylor instability, along with a video to watch if/when you're stoned.


We've talked about Rayleigh-Taylor instability before. It's what happens when you put a dense liquid on top of a less-dense liquid. Plumes of liquid erupt and curl, making beautiful, ever-shifting patterns. The exact patterns depend on the relative density of both liquids and the time they're given to mix together. If the liquids are dried or frozen in place quickly, the pattern can be large cumulus cloud blobs of color. Give them some more time and they can be more elaborate, feather-like structures. Eventually, though, they're going to have to mix together into a uniform substance or re-separate completely, right?

Wrong! This experiment shows lots of ways that the fluids can mix together. There are two different sequences of the fluids mixing. Both look very cool. The first is classic — two different liquids, each of uniform density, the dense one on top of the less-dense one. The barrier between them is removed and they mix, with the mixing region filling up the entire area. The second one changes it up a little; instead of each of the liquids being uniformly dense all the way through, each of them has a low density at the top, and gradually gets denser on the way down. Because the more-dense bottom of one liquid is on top of the less-dense top of the next, they start out the same way the other liquid did. But instead of filling the whole area, they leave the top of container untouched while a sea of roiling green liquid surges below.


Via Physics Central.

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