Cracking The Egg Sprinkler Mystery

[Ptah]

http://www.sciencefriday.com/videos/watch/10455

When engineer Tadd Truscott was in grad school, one of his classmates at MIT
suggested they spin an egg in a puddle of milk and film it with a high-speed camera.
What they saw was a tiny sprinkler system: the milk rose up the sides of the spinning
egg, shooting off at the egg's equator. This became a household science experiment for
Truscott and his kids, until one day he realized he didn't know why the milk rises up the
egg. Armed with a PhD in hydrodynamics, Truscott, now at Brigham Young University,
and colleagues including mechanical engineering student Ken Langley, set out to crack the case.

[Skinner]

1. I'm so glad you posted this. I heard it on NPR today and I was very curious.

Very cool video.

[Ptah]

2. That NPR story drove me to it.

[surrealAmerican]

3. Awesome!

The spinning egg (or pool ball) actually creates a pump via the bernoulli effect.


k & r

[tridim]

4. My mind is racing with possibilities for this pump

I bet it's very efficient too, due to extremely low friction.

What happens if you spin the ball at extremely high speed? What if the ball is massive, or tiny? What if the ball is buoyant? What happens if there is a hole in the bottom of the sphere? what happens when you spin a convex cone?

[DCKit]

5. Bastid! I was going to say exactly the same thing, not nearly as well. nt

[SolutionisSolidarity]

6. I think it has more potential as a tool for coating than as a pump.

This is basically the same thing as an uncontained centrifugal pump. There's a spinning impeller, in this case an egg, which increases the velocity of a fluid to generate flow. In the case of a normal centrifugal pump, the fluid is spun in a chamber at great speed then channeled into a pipe with a fluid that is moving at a much slower velocity, and the kinetic energy of the pumped fluid is converted into pressure. I could see this applied towards coatings though - he did seem to have a good deal of control over the droplet size, and the technology is very cheap and simple.