Capillary Rise in Nanopores: Molecular Dynamics Evidence for the Lucas-Washburn Equation

D. I. Dimitrov, A. Milchev, and K. Binder
Phys. Rev. Lett. 99, 054501 – Published 31 July 2007

Abstract

When a capillary is inserted into a liquid, the liquid will rapidly flow into it. This phenomenon, well studied and understood on the macroscale, is investigated by molecular dynamics simulations for coarse-grained models of nanotubes. Both a simple Lennard-Jones fluid and a model for a polymer melt are considered. In both cases after a transient period (of a few nanoseconds) the meniscus rises according to a (time)1/2 law. For the polymer melt, however, we find that the capillary flow exhibits a slip length δ, comparable in size with the nanotube radius R. We show that a consistent description of the imbibition process in nanotubes is only possible upon modification of the Lucas-Washburn law which takes explicitly into account the slip length δ. We also demonstrate that the velocity field of the rising fluid close to the interface is not a simple diffusive spreading.

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  • Received 30 March 2007

DOI:https://doi.org/10.1103/PhysRevLett.99.054501

©2007 American Physical Society

Authors & Affiliations

D. I. Dimitrov1, A. Milchev1,2, and K. Binder1

  • 1Institut für Physik, Johannes Gutenberg Universität Mainz, Staudinger Weg 7, 55099 Mainz, Germany
  • 2Institute for Chemical Physics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

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Vol. 99, Iss. 5 — 3 August 2007

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