(419c) Effect of Triboelectric Charges on Powder Flow: DEM Simulation with Patchy Particles and Comparison with Experiments

Once granular materials flow, particles charge because of the triboelectric effect. When particles touch each other, charges are exchanged during contact whether they are made of the same material or not. Surprisingly, when different sizes of particles are mixed together, large particles tend to charge positively while small particles charge negatively. If the particles are relatively small (typically smaller than a millimeter), the electrostatic interaction between the particles becomes significant and leads to aggregation, intermittent flows or sticking on surfaces. Studying those effects is challenging as the mechanisms that govern the triboelectric effect are not fully understood yet.

DEM simulations - We show that the patch model (or mosaic model) is suitable to reproduce numerically the flow of triboelectrically charged granular materials in rotating drum geometry. We investigate the influence of charging on the cohesion of granular materials and highlight the relevant parameters related to the patch model that influence cohesion.

Experiments – A set of experiments were performed in the same geometry with GranuDrum instrument and the ability of the powders to charge was measured with GranuCharge instrument.

The experimental and simulation results are compared to shed new light on the mechanisms of the triboelectric effect as well as on how the charging of granular materials influences cohesion. Moreover, the links between these fundamental results and industrial processes will be discussed.

Reference:

Tribocharging of granular materials and influence on their flow, N. Preud’homme, G. Lumay, N. Vandewalle and E. Opsomer, Soft Matter 19, 8911 (2023)