Putting the micro into the macro: A molecularly augmented hydrodynamic model of dynamic wetting applied to flow instabilities during forced dewetting

Keeler, J. S. ORCID: https://orcid.org/0000-0002-8653-7970, Blake, T. D., Lockerby, D. L. and Sprittles, J. E. (2022) Putting the micro into the macro: A molecularly augmented hydrodynamic model of dynamic wetting applied to flow instabilities during forced dewetting. Journal of Fluid Mechanics, 953. ISSN 0022-1120

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We report a molecularly augmented continuum-based computational model of dynamic wetting and apply it to the displacement of an externally driven liquid plug between two partially wetted parallel plates. The results closely follow those obtained in a recent molecular dynamics (MD) study of the same problem (Fernández-Toledano et al., J. Colloid Interface Sci., vol. 587, 2021, pp. 311-323), which we use as a benchmark. We are able to interpret the maximum speed of dewetting as a fold bifurcation in the steady phase diagram and show that its dependence on the true contact angle is quantitatively similar to that found using MD. A key feature of the model is that the contact angle is dependent on the speed of the contact line, with emerging as part of the solution. The model enables us to study the formation of a thin film at dewetting speeds U∗ across a range of length scales, including those that are computationally prohibitive to MD simulations. We show that the thickness of the film scales linearly with the channel width and is only weakly dependent on the capillary number. This work provides a link between matched asymptotic techniques (valid for larger geometries) and MD simulations (valid for smaller geometries). In addition, we find that the apparent angle, the experimentally visible contact angle at the fold bifurcation, is not zero. This is in contrast to the prediction of conventional treatments based on the lubrication model of flow near the contact line, but consistent with experiment.

Item Type: Article
Additional Information: Funding information: We acknowledge funding from EPSRC grants EP/W031426/1, EP/N016602/1, EP/P020887/1, EP/S029966/1 and EP/P031684/1. J.S.K. acknowledges funding from the Leverhulme Trust grant ECF-2021-017. Data availability statement: The data that support the findings of this study are openly available in figshare at https://doi.org/10.6084/m9.figshare.17277812.
Uncontrolled Keywords: contact lines,liquid bridges,thin films,condensed matter physics,mechanics of materials,mechanical engineering,applied mathematics ,/dk/atira/pure/subjectarea/asjc/3100/3104
Faculty \ School: Faculty of Science > School of Mathematics
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Depositing User: LivePure Connector
Date Deposited: 15 Dec 2022 04:08
Last Modified: 03 Jan 2023 09:34
URI: https://ueaeprints.uea.ac.uk/id/eprint/90157
DOI: 10.1017/jfm.2022.953


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