A model kinetic equation is proposed to describe the time evolution of a gas composed of particles which collide inelastically. Dissipation in collisions is described by means of a parameter which is related to the coefficient of restitution, e . The kinetic equation can be solved exactly for the homogeneous cooling state, providing explicit expressions for both the time-dependent ‘‘temperature...

This paper describes two-dimensional computer simulations of granular flow in plane hoppers. The simulations can reproduce an experimentally observed asymmetric unsteadiness for monodispersed particle sizes, but also could eliminate it by adding a small amount of polydispersity. This appears to be a result of the strong packings that may be formed by monodispersed particles and is thus a noncon...

We report on the discovery, using numerical simulations, of a segregation pattern in high-speed granular flows, which size is primarily driven by two-dimensional temperature gradients, rather than gravity. In contrast to slower flows gentle slopes, steep large particles no longer accumulate upper layers flow, but are trapped interior. The strong gradients that develop between interior flow and ...

Numerical simulations are used to test the kinetic theory constitutive relations of inertial granular shear flow. These predictions are shown to be accurate in the dilute regime, where only binary collisions are relevant, but underestimate the measured value in the dense regime, where force networks of size xi are present. The discrepancy in the dense regime is due to non-collisional forces tha...

Particle fracture, the formation of small particles as result breakage large ones, and aggregation, combination have important implications in industry (e.g. food processing, pharmaceutical production) geophysics (e.g., snow avalanches rock debris flows). Also, presence different size that from fracture aggregation can induce segregation, resulting migration to regions flow. Here, we formulate ...

Strongly vertically shaken granular matter can display a density inversion: A high-density cluster of beads is elevated by a dilute gaslike layer of fast beads underneath ("granular Leidenfrost effect"). For even stronger shaking the granular Leidenfrost state becomes unstable and granular convection rolls emerge. This transition resembles the classical onset of convection in fluid heated from ...

Bottlenecks occur in a wide range of situations from pedestrians, ants, cattle, and traffic flow to the transport of granular materials. We examine granular flow across a bottleneck using simulations of monodisperse disks. Contrary to expectations but consistent with previous work, we find that the flow rate across a bottleneck actually increases if an obstacle is optimally placed before it. Us...

In this work discrete element modeling (DEM) was applied to the flow of granular jets against a target. The resulting sheetlike or conelike formations under different conditions are described and explained by means of kinetic analysis. A qualitative and quantitative comparison with experimental results [Cheng, Phys. Rev. Lett. 93, 188001 (2007)] provides interesting insights in the theoretical ...