Make A Hole - And Sustain It Indefinitely

Mick Ohrberg writes "Florian Merkt, Robert Deegan, and Erin Rericha, all at the University of Texas, have shown that a hole created in a water and cornstarch mixture with a puff of air can be persistent if the mixture is shaken at about 120Hz with acceleration being in the 12g-25g range. The physics behind the phenomenon has not yet been explained."

Comments

Yarr

[Leffe]

The physics behind the phenomenon has not yet been explained.

Some kind of resonance... or the opposite of it?

Sorry, I'm not a physics nerd :(

Physics and particles

[GigsVT]

It seems that the world of physics as it relates to lots of macro sized particles interacting isn't very well explored.

I remember reading an article years ago, about research into mixed nuts. Basically they wanted to find out why the brazil nuts always tended to come to the top. It turns out it's a semi-complex interaction, when the can is shaken vertically, the nuts closer to the walls are pulled down due to the friction and they fall into the gap created at the bottom of the can, creating a sort of convection current. The larger brazils had less contact area with the wall and were not as likely to be pulled back down IIRC.

It's just kinda funny that we understand all kinds of interactions down on the atomic level, but are still researching basic things like the way mixed nuts or raisin bran sort and settle.

Re:Physics and particles

[oojah]

I remember reading an article years ago, about research into mixed nuts. Basically they wanted to find out why the brazil nuts always tended to come to the top. It turns out it's a semi-complex interaction, when the can is shaken vertically, the nuts closer to the walls are pulled down due to the friction and they fall into the gap created at the bottom of the can, creating a sort of convection current. The larger brazils had less contact area with the wall and were not as likely to be pulled back down IIRC.

I was under the impression that in general, larger particles move to the top because the smaller particles fit into gaps more easily and so move downwards - the larger particles therefore have to move up. I suspect that this may play a small part in mixed nuts, but there aren't any really small nuts, so it can't be that big an effect.

Interesting about the friction though! :)

Cheers,

Roger

Re:Cool and all

[djsmiley]

Firstly, i would guess that the inside of this structure is PERFECTLY round. I mean, so 100% perfect, something which we cannot create atm. Which will then be used some how. (like creating ROUND m&ms?). Still, no one know what it all means?

so...

[hookedup]

scale the whole project up, and easy access to sunken boats?

treasure is always a good incentive...

Likely the dynamic boron-mediated crosslinks

[Anonymous Coward]

So as the force from the air in the hole impacting with the edges of the hole increases as the frequency increases at some point it'll reach the point where it goes hard.

Just like if you hit silly putty with a hammer.

Cornstarch/Water a "sheer-thickening" fluid

[Salis]

Similar to the 'liquid body armor' reported on Slashdot a while back, cornstarch + water is a "sheer-thickening" fluid, or a fluid that increases its viscosity when it experiences sheer (or tangential force).

Perhaps the interaction between the cornstarch/water and the vibrations cause the cornstarch/water to increase its viscosity and "hold" up the walls of the hole.

Not explained?

[Anonymous Coward]

My physics is a bit rusty, but isn't this just a special case of a standing wave?