Slashdot Mirror
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."
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?
Time flies like an arrow. Fruit flies like a banana.
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.
There's no such thing as R.O.U.S.es...
Keep your eyes to the sky.
This would make one hell of a minefield.
"Alpha Squad Leader, what is your position?"
"Merf!"
"Alpha Squad Leader, say again?"
"Merrrrf!!"
My
Limekiller