Lattice Boltzmann simulations of apparent slip in hydrophobic microchannelsJ. Harting, C. Kunert and H. J. Herrmann
Institute for Computational Physics, University of Stuttgart Pfaffenwaldring 27, D-70569 Stuttgart, Germany
received 18 January 2006; accepted in final form 29 May 2006
published online 23 June 2006
Various experiments have found a boundary slip in hydrophobic microchannel flows, but a consistent understanding of the results is still lacking. While Molecular Dynamics (MD) simulations cannot reach the low shear rates and large system sizes of the experiments, it is often impossible to resolve the needed details with macroscopic approaches. We model the interaction between hydrophobic channel walls and a fluid by means of a multi-phase lattice Boltzmann model. Our mesoscopic approach overcomes the limitations of MD simulations and can reach the small flow velocities of known experiments. We reproduce results from experiments at small Knudsen numbers and other simulations, namely an increase of slip with increasing liquid-solid interactions, the slip being independent of the flow velocity, and a decreasing slip with increasing bulk pressure. Within our model we develop a semi-analytic approximation of the dependence of the slip on the pressure.
83.50.Rp - Wall slip and apparent slip.
68.08.-p - Liquid-solid interfaces.
47.11.-j - Computational methods in fluid dynamics.
© EDP Sciences 2006