Pile of sand
A pile of sand is a bulk material - piles of sand . It consists of a large number of small, rounded objects of almost the same size. The grains of sand can only be moved towards their neighbors by overcoming friction and thus show a certain amount of adhesion . A pile of sand contradicts the expectation that the grains roll off against each other like balls.
The angle of repose of a pile of sand is an important parameter. It cannot be increased beyond a critical size of approx. 28 ° -34 °, depending on the grain size and the humidity of the sand. If this critical angle of repose is exceeded, small avalanches occur, which restore a stable state. Piles of sand are a simple example of self-organized criticality .
Related topics
The paradox of the heap is based on the imprecise definition of the term heap .
Web links
- http://www.ornl.gov/sci/fed/Theory/tt/ttmcpat/sand.htm Plasma turbulence and heaps of sand (English)
- http://www.maths.nottingham.ac.uk/personal/etzkih/sand.html Sandpiles (English) with two simulations