Field driven charging dynamics of a fluidized granular bed

Abstract

A simplified model has previously described the inductive charging of colliding identical grains in the presence of an external electric field. Here we extend that model by including heterogeneous surface charge distributions, grain rotations and electrostatic interactions between grains. We find from this more realistic model that strong heterogeneities in charging can occur in agitated granular beds, and we predict that shielding due to these heterogeneities can dramatically alter the charging rate in such beds.

Surface contact charging

“…[2]). This differs from earlier simulations 7,8,9,10 of collisional grains in which contact times are short, and so for completeness we follow this first simulation with additional simulations in which we investigate the effect of varying .…”

“…the mean of absolute values, , ) both to provide an unambiguous measure of the fastest growth in a lattice and to facilitate comparison with prior work 7,8,9,10 . Asymptotically, the fastest growing charges dominate the mean and so the two measures produce the same results.…”

“…Modeling approaches have been presented previously 7,8,9,10 ; in the present work, each particle has the same radius, R, and is fixed in a close-packed hexagonal lattice as depicted in Fig. 2(a).…”

“…In previous work 7,8,9,10 , it was demonstrated that the mechanism of repetitive polarization and neutralization defined by Eq's [1] and [2] leads to exponential growth in charging. This occurs because the electric field defined by Eq.…”

“…In these panels, we reproduce voltage and charge plots showing that the quantitative charging behaviors in the three experiments appear to behave similarly. In this paper, we analyze this problem and show that this charging behavior is reproduced using a recently described first-principles model 7,8,9,10 . We show fits of this model to the three experiments in each panel of Fig.…”