DEM algorithms are numerical time integration schemes that perform dynamic updating of the particle’s motion throughout the duration of the simulation. The usual time integration scheme implemented is the explicit central difference procedure and is conditionally stable. This means the time step must provide numerical stability when the contact force is modeled by a linear stiffness. Therefore, the time step needs to be less than 2 over the natural circular frequency of a simple-mass system. It is typically suggested that the step value be about 5-10% of this contact time to prevent erratic behavior in the particle contact. Rule of thumb says there should be at least ten time steps between the initial contact to the rebound of the particle.