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The pressure tensor across a liquid-vapour interface

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journal contribution
posted on 14.06.2018 by C.C. Braga, Edward Smith, Andreas Nold, David Sibley, Serafim Kalliadasis
Inhomogeneous fluids exhibit physical properties that are neither uniform nor isotropic. The pressure tensor is a case in point, key to the mechanical description of the interfacial region. Kirkwood and Buff, and later Irving and Kirkwood, obtained a formal treatment based on the analysis of the pressure across a planar surface [J.G. Kirkwood and F.P. Buff, J. Chem. Phys., 17(3), (1949), J.H. Irving and J.G. Kirkwood, J. Chem. Phys. 18, 817 (1950)]. We propose a generalisation of Irving and Kirkwood’s argument to fluctuating, non-planar surfaces and obtain an expression for the pressure tensor that is not smeared by thermal fluctuations at the molecular scale and corresponding capillary waves [F.P. Buff, R.A. Lovett, and F.H. Stillinger, Jr., Phys. Rev. Lett. 15, 621 (1965)]. We observe the emergence of surface tension, defined as an excess tangential stress, acting exactly across the dividing surface at the sharpest molecular resolution. The new statistical mechanical expressions extend current treatments to fluctuating inhomogeneous systems far from equilibrium.

Funding

We acknowledge financial support from the European Research Council (ERC) through Advanced Grant No. 247031 and by the Engineering and Physical Sciences Research Council (EPSRC) of the UK through Grant No. EP/L020564.

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School

  • Science

Department

  • Mathematical Sciences

Published in

Journal of Chemical Physics

Citation

BRAGA, C.C. ...et al., 2018. The pressure tensor across a liquid-vapour interface. Journal of Chemical Physics, 149 (4), 044705.

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AIP Publishing © Authors

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VoR (Version of Record)

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This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Acceptance date

22/05/2018

Publication date

2018-07-30

Notes

This is an Open Access Article. It is published by AIP Publishing under the Creative Commons Attribution 4.0 International Licence (CC BY). Full details of this licence are available at: https://creativecommons.org/licenses/by/4.0/

ISSN

0021-9606

Language

en

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