Dry Quicksand

chessie writes "Just in time for the holidays, new and improved quicksand! The new dry quicksand is a physical curiousity, made with air and sand instead of water with porewater pressure overcoming the density of sand . It is possible to vanish into a pile of completely dry sand as well. Worse, their sand looks the same as the normal, weight-supporting variety. Obviously, the US Army wants in on it."

So how is this different from

[chjones]

lightning sand [imdb.com]?

(Oh, right, that pesky reality again.)

Re:So how is this different from

[vandon]

Looks like another test for the Mythbusters.

Re:So how is this different from

[Mattcelt]

So my question is: how difficult is it to upset the balance and cause the sand to fall into a lower energy state? If this is relatively easy, then the mixture becomes useless for most military applications.

OTOH, perhaps ground resonance imaging could be foiled by this... put a 'moat' of sorts around a concrete bunker, and if someone tried to use GRI to determine the location of the bunker, the quicksand would ruin the resolution of the resulting image. (Am I thinking this through properly?)

Okay, just one....

[chjones]

porewater pressure overcoming the density of sand

Yeah, I remember living in a crappy apartment where the porewater pressure in the shower just made everything more difficult....

Riiight.

[eingram]

What's next, dry ice?

Re:Riiight.

[boarder8925]

What's next, dry ice?

What about dry water [slashdot.org]?

Re:Riiight.

[Goeland86]

already exists. It's frozen carbon dioxide. Used to have fun in the lab with that. Take a tiny bit, put it in one of the smallest eppendorf tubes and it pops like a firecracker... scared the shit out of colleagues too.

Re:Riiight.

[MindStalker]

Swish!

Re:Riiight.

[Grab]

That noise you hear is the point going over your head...

Strange.

[BigZaphod]

I remember just a few weeks ago I was watching The Mummy on TV and there's the part where, after the big sand storm, the crashed airplane sinks in the sand. And I remember we sort of chuckled at that, but then I said, "Ya know, I don't see why quicksand would need water anyway. Air would probably work, too." And so, ya know, I just assumed that was known or something or I was completely wrong. And now this article comes out like it is some amazing new invention to use air to create quicksand.

I'm not re

Re:Strange.

[fbform]

The experiment described in the article is interesting in one particular aspect: the air was puffed and then stopped, leaving the sand far from its minimum-energy state, but at rest. At the other extreme, you have fludized beds used in industry (fluidized bed reactors, fluidized columns for heat and mass transfer, fluidized bed filters, some other applications), all of which are continuously fluidized, and are modeled better as liquids than solid particles. I wonder if the research described could have any industrial applications. Particle size classification by pulse fluidization?

Re:Strange.

[itwerx]

I said, "Ya know, I don't see why quicksand would need water anyway.

You are correct. In fact this phenomenon does occur naturally (though durned if I can find a good reference in Google, grr).

Re:Strange.

[Col. Klink (retired)]

There's also a famous scene in Lawrence of Arabia where someone gets trapped in dry quicksand.

Makes me want to dig holes in my front yard

[Marxist Hacker 42]

And bury an air compressor. Would make for an awfully neat booby trap.

Re:Makes me want to dig holes in my front yard

[Muhammar]

or even better, with the air compressor buried under anthill

Coming soon...

[RuneB]

Coming Soon to a desert near you! The New and Improved QuickSand 2004 edition, created by the amazing Dr. Detlef Lohse, is so fabulous and amazing that you'll want to get one for your desert too! With new features such as a dry mode so that it looks just like any other piece of sand, you'll never have to worry about an enemy attacking your secret desert hideout again!

And, now, with our special TV offer, you too can have this amazing new edition to protect your desert from just about anyone, for the low l

Porewater is....

[Somegeek]

"Porewater is the minute water-filled area around and between sand particles."

I had never heard the term before and it doesn't seem to be in the referenced article. I had to Google for 5 minutes before I found a decent definition.

Definition credit goes to Bob Goemans & Sam Gamble http://www.saltcorner.com/sections/guest/goemans&g amble/sandbedspart1.htm [saltcorner.com]

Favorite quote

[David Frankenstein]

Love the quote at the end...

"The U.S. Army is very interested in this," he said, "because these days, the U.S. Army tends to go to desert states."

what about...

[Bodhidharma]

Now I'm waiting for news about flame spurts and ROUSs.

Fluidized Beds

[mschaffer]

Gee, I thought that people who worked with fluidized beds knew about this particular phenomenon many, many years ago. If conditions are just right, the bed of material can stay like that for quite some time after the gas stops moving throug the bed.

Oh, well.

We can suvive perfectly well in the firswamp...

[clambake]

There's no such thing as R.O.U.S.es...

Discovery

[Anonymous Coward]

On the Discovery Channel, MythBusters drown quicksand!

Re:Discovery

[boarder8925]

That was a poor attempt at humor ("In Soviet Russia...."), and it's definitely not informative.

In that MythBusters episode, they made their own quicksand to test the myth of whether or not killer quicksand (the stuff in movies that sucks you down in two seconds) existed.

The myth was busted. ;)

Science Museum, London

[gazz]

I don't know how many of you have ever been to the Science Museum in London, but years ago in the "Launchpad" area they had a little box of sand with air puffed through it to demonstrate exactly the principal that's discussed here. I dunno about the resting state dynamics bit, but definately the general air-quicksand concept's not new to us Limeys.
I have no idea if it's still set up.

It was fun :D

New Weapon

[limekiller4]

This would make one hell of a minefield.

"Alpha Squad Leader, what is your position?"
"Merf!"
"Alpha Squad Leader, say again?"
"Merrrrf!!"

Does this make anybody else think of Dune?

[jonadab]

It sounds like a Fremen trap to me.

Re:Sinking into quicksand - Bah!

[Mattcelt]

Yes, *but* -
1) ever tried to run on the beach? How much easier do you think running would be with the sand at waist-length?
2) an armored personnel carrier, tank, or other vehicle displaces a whole lot more than a human being.
3) a standard military pack is a whole lot more dense than a human being, by design. It will sink a whole lot further.

Booby trap

[hoggoth]

cool...

I'm picturing a ring of air jets buried under the sand around my desert evil-fortress [zwolak.org]. When footstep vibrations are detected the jets pump out massive amounts of air into the sand, thus causing the victim to sink under the sand.

Color me redundant...

[slowhand]

...but:

1. Invent dry quicksand
2. Entice investors
3. ?
4. PROFIT!!!!