Researchers Discover That Sand Behaves Like Water 192
Xeger writes "University of Chicago researchers have found that streams of sand can behave in a similar manner to liquids, forming water-like droplets when poured from a funnel. To obtain these results, they dropped their expensive high-speed camera from a height of several meters and observed the sand forming into droplets — something that shouldn't happen without surface tension. These findings suggest that conventional engineering wisdom about sand, dirt and other grainy materials needs to be rethought, and that it might be possible to apply fluid dynamics to some solids problems."
They dropped their expensive camera? (Score:4, Insightful)
Haven't they heard of strobe lights?
It's the air. (Score:3, Insightful)
Maybe this tells us more about what the air is doing than what the sand is doing. Chaotic particles spiraling down end up it in each others draft and stay there. (think nascar drafting)
So about those "rivers" and "lakes" on mars (Score:3, Insightful)
If sand can flow like water then perhaps the lakes and rivers shown by "water" like flow on mars were just created by sand flow.
Re:hmm... (Score:1, Insightful)
After posting the Parent, it occurred to me that it could also be thought of in terms of the low-pressure column that is created as something falls through the air. Perhaps this is better explained in terms of the air pushing its way into the column at its less dense points.
Signed,
Anonymous Cowardon
!News (Score:4, Insightful)
For example, most houses are built to "float" in the soil like a boat. For structures that won't "float", like skyscrapers, they have to drive piles down to bedrock.
A strobe light wouldn't work for this. (Score:3, Insightful)
The strobe light effect you mention appears to slow down, stop, or reverse falling droplets, but is merely an illusion. The individual droplets in each frame are actually replaced by successive droplets that are sufficiently similar-looking to give the illusion that you're seeing one individual droplet frozen in space.
With the sand example, the droplets are visibly different in size and shape. You don't want some sleight-of-hand trick with a strobe light, where you turn out the lights and quickly put a different droplet in place. You want to keep individual droplets in frame and follow them as they form and fall. Having the camera fall in unison with the sand seems like a pretty good way to do it.
Since the flow at the beginning is not laminar (Score:2, Insightful)
everything else is kinda moot.
1) How uniform are the sizes of each grain?
2) Static charges?
3) Aerodynamics? (see 1)
It may appear to behave like water, no chance I am going to wash my knob with it though.