Similarity of electroosmotic flows in nanochannels

Abstract

This paper investigates the similarity of electroosmotic flows in nanochannels numerically using the NEMD method and therefore analyzes the applicability of the embedding technique. The results indicate that the near-wall ion distribution is greatly influenced by the wall charge density, the ion arrangement and the interaction between ions and walls. If all these factors are same, the electroosmotic flows in different channel sizes are of similarity, which is to say that the ion distributions close to walls are same and the velocities across the channel are similar. The embedding method is available once the similarity holds. One can predict the ion distributions and fluid flow in larger channels using the continuum equations by introducing MD results of near-wall effective potential or transport coefficients of smaller channels. The results also suggest the similarity is preferred to the channel size larger than 10 times diameter of fluid molecules.

Keywords:

• Electroosmotic flow
• Molecular dynamics
• Similarity
• Embedding method

Acknowledgements

The Present work is supported by the NTC M04-CD01 and NSF-061308. The authors would like to thank the helpful discussions from Dr Qiao, R and Dr Pan, N.