Enhanced dynamic tribocharging model for sliding particles via contact area

Abstract Particle-tribocharging occurs due to collisions and friction against a metal chute during the feeding process, driven by the difference in work functions between the materials. This study aims to enhance the fidelity of discrete element method (DEM) simulations under complex working conditions. The influence of the contact area is investigated through theoretical, simulation, and experimental approaches. The key parameters of PETG particles, including restitution coefficient, friction coefficient, and surface energy, are calibrated. The simulated angle of repose (AoR) showed a minimal deviation of only 0.38% from experimental results, confirming the accuracy of the calibrated parameters. A tribocharging model incorporating contact area is derived, along with calculation methods for saturation surface charge density and the charging coefficient. Simulations are carried out under varying sliding distances, inclination angles, and particle sizes. The results demonstrate that accounting for contact area significantly improves the agreement between DEM simulation and experimental measurements. Furthermore, a coarse-graining methodology is developed for simulating micrometre-scale particle tribocharging. When applied to a Hertz-Mindlin model with included adhesion and electrostatic forces, the error introduced by coarse-graining is maintained within 5%. These findings collectively validate the proposed contact-area-enhanced model as an accurate and efficient approach for simulating particle tribocharging in complex scenarios.