Charge dynamics in a model for grains electrization

In this work we investigate a model for the dynamics of granular electrization using event-driven simulations and approximate calculations. The model is defined as a mixture of isolating grains of different species confined in a cubic box. During the collisions, the grains and the walls can acquire electric charge via tribocharging. We focus on the dynamics of charge exchange, and calculate the time evolution of the total charge in each species, that presents a double exponential behavior in the case of zero gravitational field. For non-zero field, a stretching of the curve is present, caused by the resulting density and velocity profiles.