The basic principles of DEM(discrete element model), and the equations of particle motion and models of particleparticleinteraction are introduced.
介绍了离散元（DEM）方法的基本原理、 颗粒运动控制方程和颗粒相互作用力的数学模型。
2
Fifthly, based on the consideration of sediment diffusion because of sediment particleinteraction, the equation of vertical distribution of sediment concentration is derived.
五是在考虑泥沙颗粒碰撞扩散的基础上，推导了泥沙浓度沿垂线的分布规律。
3
A discharge model on the sputtering hollow cathode discharge (SHCD) copper ion laser is established, its characteristics of discharge, sputtering and the particleinteraction processes are analysed.