Roughness induced boundary slip in microchannel flows

Abstract

Surface roughness becomes relevant if typical length scales of the system are comparable to the scale of the variations as it is the case in microfluidic setups. Here, an apparent boundary slip is often detected which can have its origin in the assumption of perfectly smooth boundaries. We investigate the problem by means of lattice Boltzmann (LB) simulations and introduce an ``effective no-slip plane'' at an intermediate position between peaks and valleys of the surface. Our simulations show good agreement with analytical results for sinusoidal boundaries, but can be extended to arbitrary geometries and experimentally obtained surface data. We find that the detected apparent slip is independent of the detailed boundary shape, but only given by the distribution of surface heights. Further, we show that the slip diverges as the amplitude of the roughness increases.

4 pages, 6 figures

References in corpus (4)

• Slippage of water past superhydrophobic carbon nanotube forests in microchannels
• Surface Roughness and Hydrodynamic Boundary Conditions
• Large-scale lattice Boltzmann simulations of complex fluids: advances through the advent of computational grids
• Lattice Boltzmann simulations of apparent slip in hydrophobic microchannels

Cited by in corpus (20)

• Slip flow over structured surfaces with entrapped microbubbles
• Wetting, roughness and flow boundary conditions
• Random-roughness hydrodynamic boundary conditions
• Particles-on-Demand for Kinetic Theory
• Lattice Boltzmann simulations of anisotropic particles at liquid interfaces
• Wetting on Nanorough Surfaces
• Contact angle determination in multicomponent lattice Boltzmann simulations
• Lattice Boltzmann simulations in microfluidics: probing the no-slip boundary condition in hydrophobic, rough, and surface nanobubble laden microchannels
• Simulations of slip flow on nanobubble-laden surfaces
• Drag force on a sphere moving towards an anisotropic super-hydrophobic plane
• Simulation of fluid flow in hydrophobic rough microchannels
• Effective slip-length tensor for a flow over weakly slipping stripes
• Rheological study of polymer flow past rough surfaces with slip boundary conditions
• Front pinning in capillary filling of chemically coated channels
• Quantification of the performance of chaotic micromixers on the basis of finite time Lyapunov exponents
• Droplet transport in a nanochannel coated by hydrophobic semiflexible polymer brushes: the effect of chain stiffness
• Universality in statistics of Stokes flow over no-slip wall with random roughness
• Diffusion between evolving interfaces
• Multiscale analysis of the particles on demand kinetic model
• The effective slip length and vortex formation in laminar flow over a rough surface