Discrete Element Simulation of Granular Particles in a Rotating Cylinder

The objective of this contribution is to present a numerical simulation method to model the motion of a packed bed on a moving grate or in a rotary kiln using object-oriented techniques. The packed bed can be described as granular material consisting of a large number of particles. The method chosen is the Lagrangian time-driven method and it uses the position, the orientation, the velocity and the angular velocity of particles as independent variables. These are obtained by time integration of the three-dimensional dynamics equations which were derived from the classical Newtonian mechanics approach based on the second law of Newton for the translation and rotation of each particle in the granular material. This includes keeping track of all forces and moments acting on each particle at every time-step. Particles are treated as contacting visco-elastic bodies which can overlap each other. Contact forces depend on the overlap geometry, material properties and dynamics of particles and include normal and tangential components of repulsion force with visco-elastic models for energy dissipation through internal and surface friction. The resulting equations of particle motion are solved by the Gear predictor?corrector scheme of fifth-order accuracy. A discrete element method (DEM) study is conducted to investigate the mixing characteristics of spherical particles and flow regimes of a rotating tumbler. The back ground version of DEM and time integration algorithm are developed and implemented into C++ code. The implementation of time-integration algorithm is verified by simple test concerning particle-particle, particle-wall interaction for which analytical expression exist. In this paper particle force due to different material property are investigated.