====== Sand pile 'revolving rivers' ======

>Sandpiles have received considerable interest because of their intrinsic scientific interest both from the fundamental and applied points of view, and also because they are simple examples of complex systems whose behavior has been used in an attempt to explain a variety of physical, chemical, biological and social phenomena"\\ \\ [source below]

A 'normal' conical sand pile tends to feature the well known 'avalanche' mechanism (see : [[content:mathematics:self-organized_criticality]])

>Conventional understanding of sandpile formation is that as grains of sand are poured onto a horizontal surface, a conical pile develops which grows intermittently through avalanches that 'adjust' the angle of repose of the pile about some critical value, or, at least, keep it between two critical values.\\ \\ [source below]

In 1995 however, a newly observed type of sand pile growth was recorded at the University of Havana in Cuba. Involving the so-called 'Sandpile formation by revolving rivers' phenomenon - which has now been replicated and observed in multiple experiments worldwide.

How the revolving 'rivers' emerge, and why they rotate around the pile, is still unknown.

For technical details see :[[https://arxiv.org/pdf/cond-mat/0206493.pdf|'Sandpile formation by revolving rivers' ]]arXiv: //Condensed Matter /// 0206493

//Note:// A video of the phenomenon can be viewed [[https://www.youtube.com/watch?v=dATX3Vt0268|here]]

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Also see : [[content:earth_sciences:sand_dunes]]