A macroscopic donor–acceptor-based discrete element model for contact electrification of insulating granular materials

Accurate modeling of contact electrification (CE) in insulating materials are essential for predicting and controlling their behavior. Here we propose a mesoscopic model based on the donor–acceptor mechanism, incorporating findings on surface patch features of identical dielectric materials from CE experiments. This model enables us to reproduce the charge transfer process and develop a macroscopic model that statistically captures this process. We implemented the macroscopic model in the discrete element code LIGGGHTS and validated its performance through comparisons with granular-vibration CE experiments. The results demonstrate the reliable performance of this model, as evidenced by the close agreement in overall particle charge distributions with experimental data. Furthermore, the model consistently reproduces the size-dependent bipolar charging feature. Our numerical tests also highlight the importance of stochastic discharging after breakdown and the influence of boundary conditions, which can reduce the mean charges and increase the variances, providing a better fit with experimental observations.