Slow-Mo Non-Newtonian Fluid on a Speaker

So today I am going to do everyone’s favorite non-Newtonian experiment. I am going to put this corn starch and water solution on this speaker, but I want to do this scientifically.

So I am shooting it with a high-speed camera, and I am going to vary the frequency and the amplitude and see what factors really give us the best corn starch monster. It still very much looks like a liquid at this point, but as I increase the amplitude, you can kind of tell that it is not moving as smoothly as it should anymore. You can see at this amplitude it starts to jump around a little bit.

Now I want to try to increase the frequency and see what effect that has. You are now at about 20 hertz, which is the frequency recommended by some scientific papers that have studied this phenomenon. I’ll up the amplitude a little bit. That is incredible. That is awesome.

Now I am going up to about 22 hertz, seeing nicer structures. But it is really tough to tell because it is somewhat random. Sometimes it just turns into a blob like that, and other times you get some really cool things forming. I am about 34 hertz here and we are not seeing a lot of structure. It seems like at these higher frequencies it just sort of turns into a blob.

Interesting how it becomes more coherent and smoother, actually, at the higher frequencies. Wow. That’s interesting. In the high speed, you can clearly see that the inertia of the thing is keeping it off the speaker entirely. That is really cool. So it is just getting kind of bumped with that frequency. It is not really sticking around. That is why you probably need a lower frequency.

Oh. Well, that is the end of that. So how do non-Newtonian fluids work? Well, the corn starch and water is really a suspension. That is, these tiny little grains of starch suspended in water. So when you try to move that fluid slowly, the starch has time to get out of the way of each other because it is lubricated by all those water molecules in between.

But if you try to get it to go fast—and that is, there is a lot of sheer, which means there are some places that are going faster than others—well, then all of the starch grains kind of get stuck up against each other. And they can’t flow past each other. So at that point, it becomes like a solid and less like a liquid.

You know, this kind of reminds me of traffic in LA where I have been recently. If there are not that many cars on the road, it is basically like having a small amount of starch particles in your water, and everything flows very smoothly. But as soon as you get to rush hour and you have some cars which are trying to floor it down the highway, plus there are all of these cars, which are like our starch particles, on the highway, then suddenly everything gets clogged, and you are basically in what is a solid.

So traffic might be an example of something that is a non-Newtonian fluid. It flows very well when there aren’t very many particles or when it is going quite slowly, but as you try to increase the number of cars and go really fast, then everything kind of gets clogged up.