Sols, solides, structures, risques

I present two series of particle dynamics simulations to investigate the intrinsic and emergent length and time scales in granular flows. Our simulation data suggest that the rheology is controlled by at least two emerging length scales depending on the inertial nature of the flow and the roughness of boundary elements. It is also found that all  characteristic times boil down to two time scales whose ratio controls the rheological behavior (effective friction and solid fraction). These results are relevant to the definition of the representative volume element and quasi-static conditions.