Comparisons of diffusive and viscous contributions to transport coefficients of light gases in single-walled carbon nanotubes

Bhatia, Suresh K. ; Chen, Haibin ; Sholl, David S. (2005) Comparisons of diffusive and viscous contributions to transport coefficients of light gases in single-walled carbon nanotubes Molecular Simulation, 31 (9). pp. 643-649. ISSN 0892-7022

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Related URL: http://dx.doi.org/10.1080/00268970500108403

Abstract

We examine here the relative importance of different contributions to transport of light gases in single walled carbon nanotubes, using methane and hydrogen as examples. Transport coefficients at 298 K are determined using molecular dynamics simulation with atomistic models of the nanotube wall, from which the diffusive and viscous contributions are resolved using a recent approach that provides an explicit expression for the latter. We also exploit an exact theory for the transport of Lennard-Jones fluids at low density considering diffuse reflection at the tube wall, thereby permitting the estimation of Maxwell coefficients for the wall reflection. It is found that reflection from the carbon nanotube wall is nearly specular, as a result of which slip flow dominates, and the viscous contribution is small in comparison, even for a tube as large as 8.1 nm in diameter. The reflection coefficient for hydrogen is 3-6 times as large as that for methane in tubes of 1.36 nm diameter, indicating less specular reflection for hydrogen and greater sensitivity to atomic detail of the surface. This reconciles results showing that transport coefficients for hydrogen and methane, obtained in simulation, are comparable in tubes of this size. With increase in adsorbate density, the reflection coefficient increases, suggesting that adsorbate interactions near the wall serve to roughen the local potential energy landscape perceived by fluid molecules.

Item Type:Article
Source:Copyright of this article belongs to Taylor and Francis Ltd.
Keywords:Transport Coefficients; Single-walled Carbon Nanotubes; Lennard-jones Fluids; Maxwell Coefficients
ID Code:2796
Deposited On:08 Oct 2010 11:50
Last Modified:16 May 2016 13:42

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