Lattice-Boltzmmann simulations of the sedimentation of charged disks

TL;DR

This study uses Lattice-Boltzmann simulations to analyze how charged disk particles sediment in fluid, revealing shape-dependent effects and high-charge behavior where disks behave more like spheres.

Contribution

It introduces detailed simulations of charged disk sedimentation, explicitly modeling hydrodynamic and electrostatic forces, and compares shape effects with spheres.

Findings

Disks and spheres show different sedimentation velocity dependence on Debye length.

High charge causes disks to behave hydrodynamically more like spheres.

Shape influences sedimentation behavior at moderate charges.

Abstract

We report a series of Lattice-Boltzmann simulations of the sedimentation velocity of charged disks. In these simulations, we explicitly account for the hydrodynamic and electrostatic forces on disks and on their electrical double layer. By comparing our results with those for spheres with equal surface and charge, we can clarify the effect of the particle shape on the sedimentation process. We find that disks and spheres exhibit a different dependence of the sedimentation velocity on the Debye screening length. An analysis of the behavior of highly charged disks (beyond the scope of the linearized Poisson-Boltzmann equation) shows that, in that regime, the charge dependence of the sedimentation velocity of disks and spheres is similar. This suggests that, at high charge, the effective hydrodynamic shape of the disks becomes more spherical.