Hey it's me Destin welcome to Smarter Every Day
and today we're going to show you some pretty cool
high speed, and it has nothing to do with all those assault rifles.
It's actually much sweeter than that, literally.
Check this out. It is a
jar of honey.
So, I know this sounds a little strange
but we've got a high speed camera setup, and we are going to show you
something called the liquid rope coil effect. This is how it works.
You just put some of the honey on this chopstick here,
and just drip it down. And look at this.
Check out that. How cool is that.
It has to do with the viscosity of the fluid, and basically the liquid is piling
up. So I think this is really really neat, so we're gonna get a little bit of
high speed of it, and then after that we're going to discuss
this in more detail. Fluid dynamics are awesome.
It's tempting to think that this would be an easy math problem but it turns out people have been studying
this for fifty years. To explain, let me show you the variables.
This section is call the coil, and this section is called the tail.
The coil and the tail together make up the total height, H. The mass flow rate of the material
is Q, and the initial radius at the top of the tail is called
"a sub zero". We'll call the radius at the bottom "a sub one".
And the exciting part is the angular coiling frequency, which is omega.
The fluid itself also has internal properties that we have to consider. Density is rho
and the surface tension coefficient is gamma. The kinematic viscosity is nu.
OK simply put, viscosity is
the measure of the thickness of a fluid. Viscosity is the measure of a fluid to
resist a sheer or tensile stress. Dynamic viscosity is measured in
Poise, whereas kinematic viscosity is measured in Stokes.
Kinematic viscosity is also referred to as the Diffusivity of Momentum.
And that makes sense if you think about it, to diffuse momentum throughout a fluid.
As you can see here, obviously the molasses honey mixture is the most viscous.
OK if these big words are boring you, just wait. There's a shower scene for you.
But if you're like me and you want to understand what's going on and you want to know the math, let's do this.
What you're looking at here are the four different types of flow that scientists can describe
using the variables that we defined earlier. Let's start here with this one.
This is the viscous flow regime. The way it works is as H, or the height that the
fluid is dropped from is relatively small, the flow has to
naturally go into a spiral because the fluid has to get out of the way of itself.
Now the interesting thing about the equation used to define the coiling frequency is
that it doesn't even include the kinematic viscosity of the fluid. That's interesting
seeing how it's called the viscous flow regime. OK the second condition we're talking about
here is called the gravitational flow regime. Basically the way it works is
as that height increases, gravity begins to take over and stretch
the fluid. So basically the viscosity of the fluid is resisting that
stretching, and that's why the equation there shows that kinematic viscosity starts to
come into play. And that's where the coiling becomes uniform and stable.
That's the exact condition that we were filming with the high speed camera earlier.
The third condition we're gonna talk about is called the intertial regime. Now as height
gets very very long what happens is that fluid becomes very fast
and very very skinny. Now you noticed in the equation that the radius of
the coil at the bottom is factored into the denominiator and raised to the tenth power.
Now if you think about it, that means the smaller the radius gets
the higher the coiling frequency, which makes sense. OK the fourth regime
is why I love science. All we know is that somewhere between the gravitational
regime and the intertial regime, everything goes out the window. All of a sudden
you'll go from a steady state coil to some erattic figure eight pattern or something stranger
but if you raise it just a little bit more, all of a sudden you're steady state again.
Even more, and you're back on stable. Everything is erratic. The frequency
is varying wildly, but it seems to have some sort of pattern but we don't know why.
It's very interesting and there has been a very complex study done on it and I'll leave the link in the
description too that so you can check it out yourself. I think it's amazing that we as humans can
conquer so many things about the world around us but we still struggle with the smallest of things.
If you're interested in knowing why I did this video I'll leave that info in the description as well.
Boy that got weird in a hurry didn't it. Every single day
you can check out the liquid rope coil effect in your own shower. It's pretty easy. Just take your
shampoo, which is a pretty viscous fluid, and throttle the flow rate
and the height until you get the right combination and then boom.
You lock in on the liquid rope coil effect. It's pretty cool.
You can change things and see how the variables effect it's action. Anyway,
I'm not responsible for any extra shampoo you end up using.
I'm Destin. You're getting Smarter Every Day. Have a good one.
[ Captions by Andrew Jackson ]