Rheology and friction in dense granular materials: discrete simulation of plane shear flow in three dimensions
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)Abstract
Rheology and the nature of friction in dense granular matter are essential to understanding of granular flows, such as debris flow, landslide, and seismic slip of faults. The present understanding mainly involves two extreme flow regimes: fast flow of gas and quasi-static flow of dense packing. While the rheology in the former regime is well known in the form of the Bagnold's law, the rheology in the latter is still not established.
In order to understand the granular rheology in a unified view, an extensive discrete element simulation on a three dimensional granular material subjected to plain shear is performed.
It is found that the rheology is described by a power law with respect to a nondimensional number that is referred to as the inertial number. This power law is valid regardless of the flow regime; from the Bagnold to dense quasistatic flow. We also found that the friction coefficient and the volume fraction in an isobaric condition obey power laws with intercepts. In these power laws, the exponents do not seems to depend on the model details.