The particle-scale dynamics of granular materials have commonly been characterized by the self-diffusion coefficient D. However, this measure discards the collective and topological information known to be an important characteristic of particle trajectories in dense systems. Direct measurement of the entanglement of particle space–time trajectories can be obtained via the topological braid ent...

The influence of periodic vibrations on the granular flow of materials is of great interests to scientists and engineers due to both theoretical and practical reasons. In this paper, the stability of a vertically vibrated granular layer is examined by linear stability analysis. This includes two major steps, firstly, the base state at various values of mass holdup (Mt) and energy input (Qt) is ...

We study strain localization in slow shear flow focusing on layered granular materials. A heretofore unknown effect is presented here. We show that shear zones are refracted at material interfaces in analogy with refraction of light beams in optics. This phenomenon can be obtained as a consequence of a recent variational model of shear zones. The predictions of the model are tested and confirme...

One challenge of todays research on particle systems is the realistic simulation of granular materials consisting of many thousands of particles with peculiar contact interactions. In this study, molecular dynamics (MD, also called discrete element method, DEM) is introduced for the simulation of many-particle systems. A wide class of realistic contact models is presented, involving dissipation...

Bulk density is an important process parameter for machines that transport, feed or process granular materials. Certain process variables have been shown to increase bulk density, such as the channel geometry at machines with rotational helical elements, the shape, dimensions and dimension distribution of granules, pressure, temperature, and vibration of the granular layer. The effect of the ra...

Granular materials in a split-bottom ring shear cell geometry show wide shear bands under slow, quasi-static deformation. From discrete element simulations (DEM), continuum fields like the deformation gradient and stress can be computed with the goal to formulate objective constitutive relations for the flow behavior. From a single simulation only, by applying timeand (local) space-averaging, y...

Submitted for the MAR10 Meeting of The American Physical Society Jamming in Granular Polymers and Frictional Granular Assemblies LENA LOPATINA, Kent State University, CHARLES REICHHARDT, CYNTHIA REICHHARDT, Los alamos National Laboratory — Jamming has attracted growing attention as a possible unifying theme for granular materials, glasses and threshold behaviour in materials. Recent results for...

At the core of equilibrium statistical mechanics lies the notion of statistical ensembles: a collection of microstates, each occurring with a given a priori probability that depends on only a few macroscopic parameters, such as temperature, pressure, volume, and energy. In this review, we discuss recent advances in establishing statistical ensembles for athermal materials. The broad class of gr...

Constitutive relations for two-dimensional deformations of cohesionless granular materials are considered. The granular materials are assumed to be isotropic and rate-independent. One of the current trends in modelling the behaviour of granular materials is to study constitutive relations of the hypo-elastic The general hypo-elastic constitutive relation, originally proposed by Tr~esdell ,~ is ...