Dry Quicksand

 


 

Reports that travelers and even whole vehicles have instantaneously vanished by sand have often been dismissed as products of fantasy. Rightly so? Our latest experiments show that such a dry quicksand may exist, and that objects can sink up to many diameters deep into very loose, fine sand.

 

Sand supports weight. Force chains are known to play a prominent role therein. We considerably weaken the force chain structure by letting air flow through very fine sand. Even when the air is turned off and the bed has settled, the prepared sand does not support weight: Balls sink into the sand up to five diameters deep. We call this state of sand dry quick sand. The state is not to be confused with the normal quick sand which is a mixture of sand, clay, and water. The final depth the ball reaches scales linearly with its mass and above a threshold mass, a sand jet is formed which shoots sand straight and violently into the air. Read all about it in the 9 December 2004 issue of Nature.

 

See the web pages of the research group:

Physics of Fluids Department of Science and Technology University of Twente The Netherlands

 

More information:

Video material

Photo material

How to create a dry quicksand

Drag in dry quicksand

Granular jets

 

See also our movies for the:

Gallery of Fluid Motion

and our other publications in Nature and Science.