On the phase-field modelling of a miscible liquid/liquid boundary
On the phase-field modelling of a miscible liquid/liquid boundary
Mixing of miscible liquids is essential for numerous processes in industry and nature. Mixing, i.e. interpenetration of molecules through the liquid/liquid boundary, occurs via interfacial diffusion. Mixing can also involve externally or internally driven hydrodynamic flows, and can lead to deformation or disintegration of the liquid/liquid boundary. At the moment, the mixing dynamics remains poorly understood. The classical Fick's law, generally accepted for description of the diffusion process, does not explain the experimental observations, in particular, the recent experiments with dissolution of a liquid solute by a liquid solvent within a horizontal capillary \cite{Stevar2012}. We present the results of the numerical study aimed at development of an advanced model for the dissolution dynamics of liquid/liquid binary mixtures. The model is based on the phase-field (Cahn-Hilliard) approach that is used as a physics-based model for the thermo- and hydrodynamic evolution of binary mixtures. Within this approach, the diffusion flux is defined through the gradient of chemical potential, and, in particular, includes the effect of barodiffisuon. The dynamic interfacial stresses at the miscible interface are also taken into account. The simulations showed that such an approach can accurately reproduce the shape of the solute/solvent boundary, and some aspects of the diffusion dynamics. Nevertheless, all experimentally-observed features of the diffusion motion of the solute/solvent boundary, were not reproduced.
miscible liquids, diffusive interface, non-fickian diffusion, dynamic surface tension, cahn–hilliard approach
48-58
Xie, Ruilin
7658553d-bd10-465f-ac8b-f79194fed5ec
Vorobev, Anatoliy
911a4e1e-0c34-4297-b52e-c22a2b9dec01
15 February 2016
Xie, Ruilin
7658553d-bd10-465f-ac8b-f79194fed5ec
Vorobev, Anatoliy
911a4e1e-0c34-4297-b52e-c22a2b9dec01
Abstract
Mixing of miscible liquids is essential for numerous processes in industry and nature. Mixing, i.e. interpenetration of molecules through the liquid/liquid boundary, occurs via interfacial diffusion. Mixing can also involve externally or internally driven hydrodynamic flows, and can lead to deformation or disintegration of the liquid/liquid boundary. At the moment, the mixing dynamics remains poorly understood. The classical Fick's law, generally accepted for description of the diffusion process, does not explain the experimental observations, in particular, the recent experiments with dissolution of a liquid solute by a liquid solvent within a horizontal capillary \cite{Stevar2012}. We present the results of the numerical study aimed at development of an advanced model for the dissolution dynamics of liquid/liquid binary mixtures. The model is based on the phase-field (Cahn-Hilliard) approach that is used as a physics-based model for the thermo- and hydrodynamic evolution of binary mixtures. Within this approach, the diffusion flux is defined through the gradient of chemical potential, and, in particular, includes the effect of barodiffisuon. The dynamic interfacial stresses at the miscible interface are also taken into account. The simulations showed that such an approach can accurately reproduce the shape of the solute/solvent boundary, and some aspects of the diffusion dynamics. Nevertheless, all experimentally-observed features of the diffusion motion of the solute/solvent boundary, were not reproduced.
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Accepted/In Press date: 12 November 2015
e-pub ahead of print date: 12 November 2015
Published date: 15 February 2016
Keywords:
miscible liquids, diffusive interface, non-fickian diffusion, dynamic surface tension, cahn–hilliard approach
Organisations:
Energy Technology Group
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Local EPrints ID: 384010
URI: http://eprints.soton.ac.uk/id/eprint/384010
ISSN: 0021-9797
PURE UUID: 09f3966f-ed57-46f1-90a2-7929cf6b0762
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Date deposited: 07 Dec 2015 10:44
Last modified: 15 Mar 2024 03:30
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Author:
Ruilin Xie
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