Discrete Element Simulation of the Electrostatic Effect On Particle Mixing in Vibrating Beds

Due to particle-particle and particle-wall interactions, it is inevitable to generate electrostatic charges in a vibrating bed of granular materials. Because the electrostatic phenomenon can influence the flow dynamics in the bed, it is important to analyze the mechanism of electrostatic charging in such granular flow systems. In this study, a numerical model based on Discrete Element Method (DEM) is introduced to investigate the effects of vibrating frequency and amplitude on the electrostatic charging. The simulation model can be used to validate experimental data in the literature. With the increase of vibrating frequency and amplitude, the saturated charge on the particles will increase and the time required for the particles to reach the electrostatic equilibrium state will decrease. With the inclusion of electrostatic charge generation and transfer using the above DEM model, the particle mixing in the vibrating bed can be investigated. A new mixing index is introduced to quantify the mixing degree of different particles. It is concluded from the simulation results that the electrostatic effect can improve the particle mixing and particles in the vibrating bed can take less time to reach the well mixed state.