An Eulerian model to describe the behavior of electrically charged particles, which considers charge separation and transfer between particles of two separate species, is developed using the kinetic theory of granular flows. A transport equation for the charge of each particle species is obtained, incorporating the effect of the charge–velocity correlation. Closures for the collisional diffusion of charge and for the charge-velocity covariance are obtained. The developed model is applied to steady-state simulations in a one-dimensional domain with no advection, neglecting momentum transport and assuming a constant granular temperature for the solid species. While this is only a preliminary test of the model, which will require further validation, the results show the prediction of bipolar charging when the particles have different sizes, even though they are made of the same material. This phenomenon is analyzed and is shown to be driven by the electric field produced by the charge accumulated on the particles.

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