J. Phys. I France
Volume 6, Number 6, June 1996
Page(s) 823 - 836
DOI: 10.1051/jp1:1996244
J. Phys. I France 6 (1996) 823-836

Simulations of Dense Granular Flow: Dynamic Arches and Spin Organization

S. Luding1, J. Duran2, E. Clément2 and J. Rajchenbach2

1  Institut für Computeranwendungen 1, Pfaffenwaldring 27, 70569 Stuttgart, Germany
2  Laboratoire d'Acoustique et d'Optique de la Matière Condensée URA 800 CNRS, Université Pierre et marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, France

(Received 1st December 1995, revised 1st February 1996, accepted 26 February 1996)

We present a numerical model for a two dimensional (2D) granular assembly, falling in a rectangular container when the bottom is removed. We observe the occurrence of cracks splitting the initial pile into pieces, like in experiments. We study in detail various mechanisms connected to the "discontinuous decompaction" of this granular material. In particular, we focus on the history of one single long range crack, from its origin at one side wall, until it breaks the assembly into two pieces. This event is correlated to an increase in the number of collisions, i.e. strong pressure, and to a momentum wave originated by one particle. Eventually, strong friction reduces the falling velocity such that the crack may open below the slow, high pressure "dynamic arch". Furthermore, we report the presence of large, organized structures of the particles' angular velocities in the dense parts of the granulate when the number of collisions is large.

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