Numerical Investigation of Traveling Wave Electroosmotic Flows in A Microchannel

Bo Chen, Jiankang Wu, Han Chen

Mechanics Department, Huazhong University of Science and Technology, Wuhan, China.

DOI: 10.4236/jbnb.2012.322034                

Abstract

In this paper, a coordinate transformation method (CTM) is employed to numerically solve the Poisson–Nernst–Planck (PNP) equation and Navier–Stokes (NS) equations for studying the traveling-wave electroosmotic flow (TWEF) in a two-dimensional microchannel. Numerical solutions indicate that the numerical solutions of TWEF with and without the coordinate transformation are in good agreement, while CTM effectively improves stability and convergence rate of the numerical solution, and saves computational cost. It is found that the averaged flow velocity of TWEF in a micro-channel strongly depends on frequency of the electric field. Flow rate achieves a maximum around the charge frequency of the electric double layer. The approximate solutions of TWEF with slip boundary conditions are also presented for comparison. It is shown that the NS solution with slip boundary conditions agree well with those of complete PNP-NS equations in the cases of small ratios of Electric double layer(EDL) thickness to channel depth(λD/H). The NS solution with slip boundary conditions over-estimates the electroosmotic flow velocity as this ratio(λD/H) is large.

Keywords

Traveling-Wave Electroosmotic Flow (TWEF); Coordinate Transformation Method(CTM); Electric Double Layer (EDL); Poisson-Nernst-Planck(PNP) Equations

Conflicts of Interest

The authors declare no conflicts of interest.

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