Mesoscopic Simulations of Electroosmotic Flow and Electrophoresis in Nanochannels

TL;DR

This paper reviews DPD simulations of electrolyte flow in nanochannels, presenting a method to tune slip length at boundaries, analyzing electroosmotic flow under various conditions, and exploring its impact on polyelectrolyte mobility.

Contribution

It introduces a systematic way to adjust boundary slip conditions in nanochannel simulations and analyzes their effects on electroosmotic flow and polyelectrolyte mobility.

Findings

Slip length can be tuned from negative to infinity using wall-fluid friction forces.

Analytic flow profiles agree with numerical DPD results.

EOF influence on polyelectrolyte mobility depends on the dimensionless parameter κδ_B.

Abstract

We review recent dissipative particle dynamics (DPD) simulations of electrolyte flow in nanochannels. A method is presented by which the slip length $delta_B$ at the channel boundaries can be tuned systematically from negative to infinity by introducing suitably adjusted wall-fluid friction forces. Using this method, we study electroosmotic flow (EOF) in nanochannels for varying surface slip conditions and fluids of different ionic strength. Analytic expressions for the flow profiles are derived from the Stokes equation, which are in good agreement with the numerical results. Finally, we investigate the influence of EOF on the effective mobility of polyelectrolytes in nanochannels. The relevant quantity characterizing the effect of slippage is found to be the dimensionless quantity $\kappa \delta_B$, where $1/\kappa$ is an effective electrostatic screening length at the channel boundaries.