Issue
EPL
Volume 84, Number 4, November 2008
Article Number 44003
Number of page(s) 5
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/84/44003
Published online 17 November 2008
EPL, 84 (2008) 44003
DOI: 10.1209/0295-5075/84/44003

Evidence of thin-film precursors formation in hydrokinetic and atomistic simulations of nano-channel capillary filling

S. Chibbaro1, L. Biferale2, F. Diotallevi3, S. Succi3, K. Binder4, D. Dimitrov5, A. Milchev4, S. Girardo6 and D. Pisignano6

1   Department of Mechanical Engineering, University of Tor Vergata - via del Politecnico 1, 00133 Rome, Italy, EU
2   University of Tor Vergata and INFN - via della Ricerca Scientifica 1, 00133 Rome, Italy, EU
3   Istituto per le Applicazioni del Calcolo, CNR - V.le del Policlinico 137, 00161 Rome, Italy, EU
4   Institut für Physik, Johannes Gutenberg Universität Mainz - Staudinger Weg 7, 55099 Mainz, Germany, EU
5   Institute for Chemical Physics, Bulgarian Academy of Sciences - 1113 Sofia, Bulgaria, EU
6   CNR, c/o Università degli Studi di Lecce - via Arnesano, 73100 Lecce, Italy, EU

sergio.chibbaro@gmail.com
chibbaro@iac.cnr.it

received 27 July 2008; accepted in final form 14 October 2008; published November 2008
published online 17 November 2008

Abstract
We present hydrokinetic Lattice Boltzmann and Molecular Dynamics simulations of capillary filling of highly wetting fluids in nano-channels, which provide clear evidence of the formation of thin precursor films, moving ahead of the main capillary front. The dynamics of the precursor films is found to obey a square-root law as the main capillary front, $z^{2}(t)\propto t$, although with a larger prefactor, which we find to take the same value for both geometries under inspection. Both hydrokinetic and Molecular Dynamics approaches indicate a precursor film thickness of the order of one tenth of the capillary diameter. The quantitative agreement between the hydrokinetic and atomistic methods indicates that the formation and propagation of thin precursors can be handled at a mesoscopic/hydrokinetic level, thereby opening the possibility of using hydrokinetic methods to space-time scales and complex geometries of direct experimental relevance.

PACS
47.11.-j - Computational methods in fluid dynamics.
68.15.+e - Liquid thin films.
81.15.-z - Mehods of deposition of films and coatings; film growth and epitaxy.

© EPLA 2008