Discrete particle simulation of particulate systems: Theoretical developments

Discrete particle simulation of particulate systems: A review of major applications and findings

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 avoid arbitrary treatments or unnecessary assumptions, and its validity is confirmed by the good agreement between the simulated and experimental results under comparable conditions. Numerical results suggest that the angle of repose increases significantly with the rolling friction coefficient and decreases with particle size.

Rolling friction in the dynamic simulation of sandpile formation

Review and extension of normal force models for the Discrete Element Method

Discrete element models for non-spherical particle systems: From theoretical developments to applications

The stratification of poured granular mixtures into layers according to particle size has long been identified as an important mechanism by which such materials segregate1,2 The implications of this effect for the process industries have also been discussed3,4 Makse et al5 suggestthat stratification takes place only when there is a marked difference in the shape of large and small grains; specifically, when the angle of repose of the coarse phase is much greater than that of the fines Our experiments show that stratification can occur in the absence of such heterogeneity of particle shapes within the mixture

Stratification in poured granular heaps

Three-dimensional particle shape descriptors for computer simulation of non-spherical particulate assemblies

Granular dynamics simulations have been carried out of vertical feed two-dimensional heap formation by a freefall method using a more realistic granule interaction law than has been employed in previous studies to permit prolonged contacts between adjacent granules. Stable heaps are found to form only on a geometrically rough base comprised of discrete particles, and heap formation is only weakly sensitive to the value of the contact friction coefficient. The appearance of avalanches, the pressure distribution on the base, and the voidage distribution are sensitive to the analytic form of the elastic component of the normal interaction, with a soft-sphere r-36 potential giving more realistic behavior than an equivalent Hooke law interaction with the same apparent spring constant. The r-36 interaction gives more realistic assembly dynamics as it introduces medium range collective motion caused by particle roughness and shape found in typical granular materials, without having to model anisotropic particles.

Granular dynamics simulations of two-dimensional heap formation

This paper describes a research programme undertaken for the solution of a serious industrial powder handling problem; the achievement of steady, controllable, reproducible discharge of a fine pharmaceutical powder from an intermediate storage vessel to the main process reactor The use of computer simulations, specifically the discrete element method (DEM) was central to the programme DEM offers explanations of material phenomenology and suggests possible practical solutions using information which may be difficult or impossible to obtain in practice using traditional observation and experimental techniques It is suggested that the programme is an example of a general strategy which may be useful when traditional heuristic, experience-based methods of powder flow problem solving prove inadequate

A DEM simulation and experimental strategy for solving fine powder flow problems

http://www.tem.uoc.gr/~nchristakis/Christakis04_4.pdf

J. Baxter

Papers

Stratification in poured granular heaps

Three-dimensional particle shape descriptors for computer simulation of non-spherical particulate assemblies

Granular dynamics simulations of two-dimensional heap formation

A DEM simulation and experimental strategy for solving fine powder flow problems

Numerical predictions of particle degradation in industrial-scale pneumatic conveyors