Hydrodynamic density-functional theory for the moving contact-line problem reveals fluid structure and emergence of a spatially distinct pattern
File(s)
Published version
Author(s)
Nold, Andreas
Goddard, Benjamin D
Sibley, David N
Kalliadasis, Serafim
Type
Journal Article
Abstract
Understanding the nanoscale effects controlling the dynamics of a contact line—defined as the line formed at the junction of two fluid phases and a solid—has been a longstanding problem in fluid mechanics pushing experimental and numerical methods to their limits. A major challenge is the multiscale nature of the problem, whereby nanoscale phenomena manifest themselves at the macroscale. To probe the nanoscale, not easily accessible to other methods, we propose a reductionist model that employs elements from statistical mechanics, namely, dynamic-density-functional theory (DDFT), in a Navier-Stokes-like equation—an approach we name hydrodynamic DDFT. The model is applied to an isothermal Lennard-Jones fluid with no slip on a flat solid substrate. Our computations reveal fluid stratification with an oscillatory density structure close to the wall and the emergence of two distinct regions as the temperature increases: a region of compression on the vapor side of the liquid-vapor interface and an effective slip region of large shear on the liquid side. The compressive region spreads along the fluid interface at a lengthscale that increases faster than the width of the fluid interface with temperature, while the width of the slip region is bound by the oscillatory fluid density structure and is constrained to a few particle diameters from the wall. Both compressive and shear effects may offset contact line friction, while compression in particular has a disproportionately high effect on the speed of advancing contact lines at low temperatures.
Date Issued
2024-12-09
Date Acceptance
2024-10-01
Citation
Physical Review Fluids, 2024, 9 (12)
ISSN
2469-990X
Publisher
American Physical Society
Journal / Book Title
Physical Review Fluids
Volume
9
Issue
12
Copyright Statement
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
License URL
Identifier
10.1103/PhysRevFluids.9.124003
Subjects
ANGLE
DYNAMICS
INTERFACE
MODEL
NANOSCALE
Physical Sciences
Physics
Physics, Fluids & Plasmas
SCALES
Science & Technology
SURFACE-TENSION
Publication Status
Published
Article Number
124003
Date Publish Online
2024-12-09