Issue 48, 2016

A Langevin model for fluctuating contact angle behaviour parametrised using molecular dynamics

Abstract

Molecular dynamics simulations are employed to develop a theoretical model to predict the fluid–solid contact angle as a function of wall-sliding speed incorporating thermal fluctuations. A liquid bridge between counter-sliding walls is studied, with liquid–vapour interface-tracking, to explore the impact of wall-sliding speed on contact angle. The behaviour of the macroscopic contact angle varies linearly over a range of capillary numbers beyond which the liquid bridge pinches off, a behaviour supported by experimental results. Nonetheless, the liquid bridge provides an ideal test case to study molecular scale thermal fluctuations, which are shown to be well described by Gaussian distributions. A Langevin model for contact angle is parametrised to incorporate the mean, fluctuation and auto-correlations over a range of sliding speeds and temperatures. The resulting equations can be used as a proxy for the fully-detailed molecular dynamics simulation allowing them to be integrated within a continuum-scale solver.

Graphical abstract: A Langevin model for fluctuating contact angle behaviour parametrised using molecular dynamics

Article information

Article type
Paper
Submitted
26 Aug 2016
Accepted
08 Nov 2016
First published
09 Nov 2016

Soft Matter, 2016,12, 9604-9615

A Langevin model for fluctuating contact angle behaviour parametrised using molecular dynamics

E. R. Smith, E. A. Müller, R. V. Craster and O. K. Matar, Soft Matter, 2016, 12, 9604 DOI: 10.1039/C6SM01980C

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