Europhys. Lett.
Volume 76, Number 2, October 2006
Page(s) 318 - 324
Section Interdisciplinary physics and related areas of science and technology
Published online 13 September 2006
Europhys. Lett., 76 (2), pp. 318-324 (2006)
DOI: 10.1209/epl/i2005-10605-1

Emergence of multi-contact interactions in contact dynamics simulations of granular shear flows

G. Lois1, A. Lemaître1, 2 and J. M. Carlson1

1  Physics Department, University of California - Santa Barbara, CA 93106, USA
2  Institut Navier-LMSGC - 2 allée Képler, 77420 Champs-sur-Marne, France

received 27 December 2005; accepted in final form 23 August 2006
published online 13 September 2006

We examine the binary collision assumption of hard-sphere kinetic theory in numerical simulations of sheared granular materials. For a wide range of densities and restitution coefficients we measure collisional and non-collisional contributions to the stress tensor and find that non-collisional effects dominate at large density and small restitution coefficient. In the regimes where the non-collisional contributions disappear, we test kinetic theory predictions for the pressure without any fitting parameters and find remarkable agreement. In the regimes where the non-collisional contributions become large, we observe groups of simultaneously interacting grains and determine the average multi-contact cluster size using measurements of spatial force correlations.

81.05.Rm - Porous materials; granular materials.
05.20.Dd - Kinetic theory.
89.75.Fb - Structures and organization in complex systems.

© EDP Sciences 2006