Journal of Physical Chemistry C | 2019
Molecular and Continuum Perspectives on Intermediate and Flow Reversal Regimes in Electroosmotic Transport
Abstract
Electroosmotic slip flows in the Debye–Huckel regime were previously investigated using molecular dynamics and continuum transport perspectives ( J. Phys. Chem. C 2018, 122, 9699). This continuing work focuses on distinct electrostatic coupling regimes, where the variations in electroosmotic flows are elucidated based on Poisson–Fermi and Stokes equations and molecular dynamics simulations. In particular, aqueous NaCl solution in silicon nanochannels are considered under realistic electrochemical conditions, exhibiting intermediate flow and flow reversal regimes with increased surface charge density. Electroosmotic flow exhibits plug flow behavior in the bulk region for channel heights as small as 5 nm. With increased surface charge density, constant bulk electroosmotic flow velocity first increases and then it begins to gradually decrease until flow reversal is observed. In order to capture the flow physics and discrete motions within electric double layer accurately, the continuum model includes overscr...