'Gas cushion' model and hydrodynamic boundary conditions for superhydrophobic textures

Abstract

Superhydrophobic Cassie textures with trapped gas bubbles reduce drag, by generating large effective slip, which is important for a variety of applications that involve a manipulation of liquids at the small scale. Here we discuss how the dissipation in the gas phase of textures modifies their friction properties. We propose an operator method, which allows us the mapping of the flow in the gas subphase to a local slip boundary condition at the liquid/gas interface. The determined uniquely local slip length depends on the viscosity contrast and underlying topography, and can be immediately used to evaluate an effective slip of the texture. Besides superlubricating Cassie surfaces our approach is valid for rough surfaces impregnated by a low-viscosity 'lubricant', and even for Wenzel textures, where a liquid follows the surface relief. These results provide a framework for the rational design of textured surfaces for numerous applications.

8 pages, 6 figures

References in corpus (4)

• A note on the effective slip properties for microchannel flows with ultra-hydrophobic surfaces
• Slip flow over structured surfaces with entrapped microbubbles
• Direct measurements of hydrophobic slippage using double-focus fluorescence cross-correlation
• Influence of the enclosed fluid on the flow over a microstructured surface in the Cassie state

Cited by in corpus (7)

• Electro-hydrodynamics near Hydrophobic Surfaces
• Enhanced slip properties of lubricant-infused grooves
• Flows and mixing in channels with misaligned superhydrophobic walls
• Effective slip over partially filled microcavities and its possible failure
• Flow-driven collapse of lubricant-infused surfaces
• Boundary conditions at the gas sectors of superhydrophobic grooves
• Multiphase unsteady Stokes flow over grooved surfaces: an analytical study