Authors: J.B. Freund
Affilation: University of California at Los Angeles, United States
Pages: 270 - 270
Keywords: electro-osmosis, nanofluidics, atomistic simulation
An atomistic simulation of an electro-osmostic flow in a 50 ° A wide channel is performed to examine models for such flows and study its physical details. The working fluid considered is a 1.1M mean concentration solution of Cl- (only negative ions for simplicity) in water. The water is modeled by the SPC/E potential and the Cl- are modeled as point charges plus an established Lennard-Jones potential. The channel walls are fixed lattices of positively charged Lennard-Jones atoms. The distribution of Cl- adjacent to the charged walls differs somewhat from theoretical predictions that assume infinitesimal ions and constant electric permittivity, and this second assumption is called into question because it is found that the waters near the wall are preferentially oriented by the local electric field, which will alter their dielectric properties. When an electric field is applied parallel to the channel walls, a velocity profile develops that is consistent with a monolayer thick Stern layer.