Molecular diffusion and slip boundary conditions at smooth surfaces with periodic and random nanoscale textures

Abstract

The influence of periodic and random surface textures on the flow structure and effective slip length in Newtonian fluids is investigated by molecular dynamics (MD) simulations. We consider a situation where the typical pattern size is smaller than the channel height and the local boundary conditions at wetting and nonwetting regions are characterized by finite slip lengths. In case of anisotropic patterns, transverse flow profiles are reported for flows over alternating stripes of different wettability when the shear flow direction is misaligned with respect to the stripe orientation. The angular dependence of the effective slip length obtained from MD simulations is in good agreement with hydrodynamic predictions provided that the stripe width is larger than several molecular diameters. We found that the longitudinal component of the slip velocity along the shear flow direction is proportional to the interfacial diffusion coefficient of fluid monomers in that direction at equilibrium. In case of random textures, the effective slip length and the diffusion coefficient of fluid monomers in the first layer near the heterogeneous surface depend sensitively on the total area of wetting regions.

30 pages, 11 figures

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Cited by in corpus (15)

• Effective slip boundary conditions for arbitrary one-dimensional surfaces
• Regularization of the slip length divergence in water nanoflows by inhomogeneities at the Angstrom scale
• Anisotropic flow in striped superhydrophobic channels
• Correlation between surface topography and slippage: a Molecular Dynamics study
• Molecular dynamics simulations of oscillatory Couette flows with slip boundary conditions
• Effective slip-length tensor for a flow over weakly slipping stripes
• Flow past superhydrophobic surfaces with cosine variation in local slip length
• Molecular dynamics simulations of the rotational and translational diffusion of a Janus rod-shaped nanoparticle
• Flows and mixing in channels with misaligned superhydrophobic walls
• Diffusion of a Janus nanoparticle in an explicit solvent: A molecular dynamics simulation study
• Interfacial friction between semiflexible polymers and crystalline surfaces
• Effective slippage on superhydrophobic trapezoidal grooves
• Wetting properties of structured interfaces composed of surface-attached spherical nanoparticles
• Lattice-Boltzmann simulations of the drag force on a sphere approaching a superhydrophobic striped plane
• Molecular dynamics simulation study of a polymer droplet transport over an array of spherical nanoparticles