Discrete element method - Wikipedia, the free encyclopedia

Discrete element method - Wikipedia, the free encyclopedia: "Outline of the method
A DEM-simulation is started by putting all particles in a certain position and giving them an initial velocity. Then the forces which act on each particle are computed from the initial data and the relevant physical laws.
The following forces may have to be considered in macroscopic simulations:
friction, when two particles touch each other;
recoil, when two particles collide;
gravity (the force of attraction between particles due to their mass), which is only relevant in astronomical simulations.
On a molecular level, we may consider
the Coulomb force, the electrostatic attraction or repulsion of particles carrying electric charge;
Pauli repulsion, when two atoms approach each other closely;
van der Waals force.
All these forces are added up to find the total force acting on each particle. 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. Then, the new positions are used to compute the forces during the next step, and this loop is repeated until the simulation ends.
Typical integration methods used in a discrete element method are:
the Verlet algorithm,
velocity Verlet,
the leapfrog method"