Particle dynamics simulations of the effect of particle size distribution on triboelectric charging in granular insulator systems

Triboelectric charging occurs in granular materials composed of insulating particles even when all particles are composed of the identical material. Large scale particle dynamics simulations are used here to address triboelectric charging in such systems. The model used in the simulations is based on the presence of electrons trapped in high energy states, which can be released during collisions with another particle and transferred to the other particle. The simulations show that triboelectric charging in these systems can be attributed to a distribution of particle sizes, such that smaller particles tend to charge negatively and larger particles tend to charge positively. This polarity of charging has been observed in field studies and laboratory experiments involving granular systems.