Simulation of the electrification of wind-blown sand.

The triboelectric charging of collision particles is essential to understand sand electrification in wind-blown sand fluxes. The physical model of electron trapped in high-energy states has been proposed to explain the triboelectric charging between identical insulating granular materials. In this study we propose an improved triboelectric charging model which combines the soft sphere model and the trapped electron model to calculate the net charge transfer during particles' collisions. Based on our charging model, we investigate the sand electrification of wind-blown sand, such as the charge flux varying with height, the charge-to-mass ratio of wind-blown sand, and the equilibrium time that the charge takes to approach a stable state. Numerical simulation results of the averaged charge-to-mass ratio in wind-blown sand fluxes are in good agreement with the experimental data.