22 results found
Sibley DN, Llombart P, Noya EG, et al., 2021, How ice grows from premelting films and water droplets., Nat Commun, Vol: 12
Close to the triple point, the surface of ice is covered by a thin liquid layer (so-called quasi-liquid layer) which crucially impacts growth and melting rates. Experimental probes cannot observe the growth processes below this layer, and classical models of growth by vapor deposition do not account for the formation of premelting films. Here, we develop a mesoscopic model of liquid-film mediated ice growth, and identify the various resulting growth regimes. At low saturation, freezing proceeds by terrace spreading, but the motion of the buried solid is conveyed through the liquid to the outer liquid-vapor interface. At higher saturations water droplets condense, a large crater forms below, and freezing proceeds undetectably beneath the droplet. Our approach is a general framework that naturally models freezing close to three phase coexistence and provides a first principle theory of ice growth and melting which may prove useful in the geosciences.
Llombart P, Noya EG, Sibley DN, et al., 2020, Rounded Layering Transitions on the Surface of Ice, PHYSICAL REVIEW LETTERS, Vol: 124, ISSN: 0031-9007
Yin H, Sibley DN, Archer AJ, 2019, Binding potentials for vapour nanobubbles on surfaces using density functional theory, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 31, ISSN: 0953-8984
Braga C, Smith E, Nold A, et al., 2018, The pressure tensor across a liquid-vapour interface, Journal of Chemical Physics, Vol: 149, ISSN: 0021-9606
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), 338 (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 et al., Phys. Rev. Lett. 15, 621–623 (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.
Nold A, González MacDowell L, Sibley DN, et al., 2018, The vicinity of an equilibrium three-phase contact line using density-functional theory: density profiles normal to the fluid interface, Molecular Physics, Vol: 116, Pages: 2239-2243, ISSN: 0026-8976
The paper by Nold et al. [Phys. Fluids 26 (7), 072001 (2014)] examined density profiles and the micro-scale structure of an equilibrium three-phase (liquid–vapour–solid) contact line in the immediate vicinity of the wall using elements from the statistical mechanics of classical fluids, namely density-functional theory. The present research note, building on the above work, further contributes to our understanding of the nanoscale structure of a contact line by quantifying the strong dependence of the liquid–vapour density profile on the normal distance to the interface, when compared to the dependence on the vertical distance to the substrate. A recent study by Benet et al. [J. Phys. Chem. C 118 (38), 22079 (2014)] has shown that this could explain the emergence of a film-height-dependent surface tension close to the wall, with implications for the Frumkin–Derjaguin theory.
Morciano M, Fasano M, Nold A, et al., 2017, Nonequilibrium molecular dynamics simulations of nanoconfined fluids at solid-liquid interfaces., Journal of Chemical Physics, Vol: 146, ISSN: 0021-9606
We investigate the hydrodynamic properties of a Lennard-Jones fluid confined to a nanochannel using molecular dynamics simulations. For channels of different widths and hydrophilic-hydrophobic surface wetting properties, profiles of the fluid density, stress, and viscosity across the channel are obtained and analysed. In particular, we propose a linear relationship between the density and viscosity in confined and strongly inhomogeneous nanofluidic flows. The range of validity of this relationship is explored in the context of coarse grained models such as dynamic density functional-theory.
Yin H, Sibley DN, Thiele U, et al., 2017, Films, layers, and droplets: The effect of near-wall fluid structure on spreading dynamics, PHYSICAL REVIEW E, Vol: 95, ISSN: 2470-0045
Nold A, Sibley DN, Goddard BD, et al., 2015, Nanoscale Fluid Structure of Liquid-solid-vapour Contact Lines for a Wide Range of Contact Angles, Mathematical Modelling of Natural Phenomena, Vol: 10, Pages: 111-125, ISSN: 0973-5348
We study the nanoscale behaviour of the density of a simple fluid in the vicinity of an equilibrium contact line for a wide range of Young contact angles θY ∈ [ 40°,135° ]. Cuts of the density profile at various positions along the contact line are presented, unravelling the apparent step-wise increase of the film height profile observed in contour plots of the density. The density profile is employed to compute the normal pressure acting on the substrate along the contact line. We observe that for the full range of contact angles, the maximal normal pressure cannot solely be predicted by the curvature of the adsorption film height, but is instead softened – likely by the width of the liquid-vapour interface. Somewhat surprisingly however, the adsorption film height profile can be predicted to a very good accuracy by the Derjaguin-Frumkin disjoining pressure obtained from planar computations, as was first shown in [Nold et al., Phys. Fluids, 26, 072001, 2014] for contact angles θY< 90°, a result which here we show to be valid for the full range of contact angles. This suggests that while two-dimensional effects cannot be neglected for the computation of the normal pressure distribution along the substrate, one-dimensional planar computations of the Derjaguin-Frumkin disjoining pressure are sufficient to accurately predict the adsorption height profile.
Sibley DN, Nold A, Kalliadasis S, 2015, The asymptotics of the moving contact line: cracking an old nut, Journal of Fluid Mechanics, Vol: 764, Pages: 445-462, ISSN: 1469-7645
Sibley DN, Nold A, Savva N, et al., 2014, A comparison of slip, disjoining pressure, and interface formation models for contact line motion through asymptotic analysis of thin two-dimensional droplet spreading, Journal of Engineering Mathematics
Nold A, Sibley DN, Goddard BD, et al., 2014, Fluid structure in the immediate vicinity of an equilibrium three-phase contact line and assessment of disjoining pressure models using density functional theory, Physics of Fluids, Vol: 26
Sibley DN, Nold A, Kalliadasis S, 2013, Unifying binary fluid diffuse-interface models in the sharp-interface limit, Journal of Fluid Mechanics, Vol: 736, Pages: 5-43
Sibley DN, Nold A, Savva N, et al., 2013, The contact line behaviour of solid-liquid-gas diffuse-interface models, Physics of Fluids, Vol: 25
Sibley DN, Nold A, Savva N, et al., 2013, On the moving contact line singularity: Asymptotics of a diffuse-interface model, European Physical Journal E, Vol: 36
Sibley DN, Savva N, Kalliadasis S, 2012, Slip or not slip? A methodical examination of the interface formation model using two-dimensional droplet spreading on a horizontal planar substrate as a prototype system, Physics of Fluids, Vol: 24
Evans JD, Sibley DN, 2010, The UCM limit of the PTT equations at a re-entrant corner, Journal of Non-Newtonian Fluid Mechanics, Vol: 165, Pages: 1543-1549
Sibley DN, 2010, Viscoelastic Flows of PTT Fluids
Evans JD, Sibley DN, 2010, The asymptotic behaviour at a re-entrant corner for a PTT Fluid in the limit of small kappa, International Conference of Numerical Analysis and Applied Mathematics 2010, Pages: 1680-1683
Evans JD, Sibley DN, 2009, Re-entrant corner flow for PTT fluids in the natural stress basis, Journal of Non-Newtonian Fluid Mechanics, Vol: 157, Pages: 79-91
Evans JD, Sibley DN, 2008, Re-entrant corner flows of PTT fluids in the Cartesian stress basis, Journal of Non-Newtonian Fluid Mechanics, Vol: 153, Pages: 12-24
Evans JD, Sibley DN, 2008, Re-entrant corner flows of PTT fluids, The XV International Congress on Rheology, Pages: 288-290
Evans JD, Sibley DN, 2007, Re-entrant corner flow of Phan-Thien-Tanner fluids, International Council for Industrial and Applied Mathematics, Pages: 2100071-2100072
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