A DEM model for contact electrification of irregular shaped particles

Contact electrification may occur during particle-particle and particle-wall collisions due to the contact potential difference. The aim of the current work is to examine the effect of particle shape on contact electrification. A discrete element method was developed to model irregular shaped particles with a multi-sphere representation and to analyse contact electrification using a condenser model. The irregular particles were modelled with a row of clustered primary spheres of various sizes and were characterized using a radial shape index that is defined as the ratio of the size between the distal and central spheres. They were subjected to tribo-electrification in a vertically vibrating container. It was revealed that the charging processes and charge distributions with different radial shape indexes exhibited distinct patterns. Specifically, particles with a large radial shape index acquired higher charge on the distal primary spheres whilst those with a smaller radial shape index gained more charge in the centre. This is due to the difference in contact probabilities associated with non-spherical particles, which leads to non-uniform charge distributions.