Discrete element method

Though DEM is very closely related to molecular dynamics, the method is generally distinguished by its inclusion of rotational degrees-of-freedom as well as stateful contact, particle deformation and often complicated geometries (including polyhedra).

Discrete element methods are relatively computationally intensive, which limits either the length of a simulation or the number of particles.

Drawbacks to homogenization of the granular scale physics, however, are well-documented and should be considered carefully before attempting to use a continuum approach.

Williams[6] showed that DEM could be viewed as a generalized finite element method, allowing deformation and fracturing of particles.

Journal articles reviewing the state of the art have been published by Williams and O'Connnor,[8] Bicanic, and Bobet et al. (see below).

Some examples are: Typical industries using DEM are: A DEM-simulation is started by first generating a model, which results in spatially orienting all particles and assigning an initial velocity.

The forces which act on each particle are computed from the initial data and the relevant physical laws and contact models.

An integration method is employed to compute the change in the position and the velocity of each particle during a certain time step from Newton's laws of motion.

A further aspect that is considered in DEM is the gas phase conduction, radiation and convection of heat in the interparticle spaces.