The couple stress of a three-dimensional vertical granular flow is investigated by means of a combined approach of discrete element method and averaging method. The velocity, mass density and couple stress are quantified under various flow conditions. The velocity and mass density profiles are...

We analyze a recently proposed continuous model for stress fields that develop in two-dimensional purely isostatic granular systems. We present a reformulation of the field equations, as a linear first-order hyperbolic system, and show that it is very convenient both for analysis and for...

A new effect of granular dynamics in a bounded domain is reported. Oscillations arise when the system evolves from a given (non-equilibrium) initial state. The oscillations obtained are of importance for vibrated granular systems since they reveal some kind of fundamental frequencies and they...

We apply a theoretical approach, originally introduced to describe aeolian ripples formation in sandy deserts, to the study of surface instability in ion-sputtered surfaces. The two phenomena are distinct by several orders of magnitudes and by several physical mechanisms, but they obey similar...

The granular gas dynamics under gravity is investigated by means of numerical simulation for the case of elastic collisions. Damped oscillations in the process of evolution to equilibrium are found and considered in detail. The nature of the oscillations is the deviation of the position of the...

The main goal of this paper is a rigorous consideration of the stress problem in some simple models of granular piles. Discrete models are considered and the transition to the continuous description is accomplished in order to find the coarse-grained average stress. Some phenomenological rules...

We study a set of nonlinear diffusion equations describing the evolution of densely packed particles under gravity subject to random vibrations. Although the thermodynamics of the model predicts no phase separation at all, the dynamics displays both normal and reverse segregation depending on...

A system of granular material resting in a bin is driven by creating voids in the bulk of the medium. Modeling the grains by a collection of mono-disperse discs, we simulate the two dimensional version of the system. Using a ‘pseudo dynamics’ to study the dynamics of the system, we observe...

The contact between spheres results in a rolling resistance due to elastic hysteresis losses or viscous dissipation. This resistance is shown to be important in the three-dimensional dynamic simulation of the formation of a heap of spheres. The implementation of a rolling friction model can...

Based on a recent model of shearing granular media we propose a new mechanism for slow dynamics. It consists of two main steps: A global optimization and a restructuring. We present numerical results of the model and its analytical treatment on the hierarchical lattice. A simplified local...