Correlation between surface topography and slippage: a Molecular Dynamics study

Abstract

Using Molecular Dynamics simulations of a polymer liquid flowing past flat and patterned surfaces, we investigate the influence of corrugation, wettability and pressure on slippage and friction at the solid-liquid interface. For one-dimensional, rectangular grooves, we observe a gradual crossover between the Wenzel state, where the liquid fills the grooves, and the Cassie state, where the corrugation supports the liquid and the grooves are filled with vapor. Using two independent flow set-ups, we characterize the near-surface flow by the slip length, $\delta$, and the position, $z_{\text{h}}$, at which viscous and frictional stresses are balanced according to Navier's partial slip boundary condition. This hydrodynamic boundary position depends on the pressure inside the channel and may be located above the corrugated surface. In the Cassie state, we observe that the edges of the corrugation contribute to the friction.

13 pages, 13 figures

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Cited by in corpus (9)

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• Stiffness-guided motion of a droplet on a solid substrate
• The Cassie-Wenzel transition of fluids on nanostructured substrates: Macroscopic force balance versus microscopic density-functional theory
• When does Wenzel's extension of Young's equation for the contact angle of droplets apply? A density functional study
• Effective slippage on superhydrophobic trapezoidal grooves
• Brushes of semiflexible polymers in equilibrium and under flow in super-hydrophobic regime
• Coalescence of sessile polymer droplets: A molecular dynamics study
• Influence of bidisperse self-assembled monolayer structure on the slip boundary condition of thin polymer films