# Segregation of charged particles in shear induced diffusion

## TL;DR

This study investigates how charged particles segregate under shear flow using particle simulations, revealing that charge magnitude influences boundary accumulation and that an optimal shear velocity maximizes segregation due to a balance of diffusive and electrostatic forces.

## Contribution

The paper introduces a particle-based simulation model incorporating electrostatic interactions to explain charge-dependent segregation in sheared granular mixtures, supported by a simple electrostatic energy model.

## Key findings

- Particles segregate by charge magnitude and position in shear flow.
- An optimal shear velocity maximizes segregation due to flux competition.
- Electrostatic potential energy favors the observed segregated configurations.

## Abstract

We study segregation of a binary mixture of similarly charged particles under shear using particle-based simulations. We simulate particle dynamics using a discrete-element model including electrostatic interactions and find that particles segregate according to their net charge. Particles that are charged twice as strong as other particles of the same electrical sign are seen more at insulating boundaries with which we shear the system. Weakly charged particles, on the other hand, stay more in the center of the sheared bed. We propose a simple model based on electrostatic potential energy to understand this segregation. The model shows that the segregated system we observe in our simulations is indeed the most favorable configuration in terms of electrostatic potential energy. Our simulations further show that for a given packing fraction there is an optimal shear velocity where the segregation maximally intensifies. We show that this maximum results from a competition between diffusional and Coulomb fluxes. For a larger shear velocity, diffusion suppresses segregation.