Wetting/dewetting transition of two phase flows in nano-corrugated channels

A lattice version of the Boltzmann kinetic equation for describing multi-phase flows in nano- and micro-corrugated devices is reviewed. To this purpose, the Shan-Chen Lattice Boltzmann model [Phys. Rev. E 47, 1815 (1993)] for non-ideal fluids is extended to the case of confined geometries with hydrophobic properties on the wall. This extended Shan-Chen method is applied for the simulation of the wetting/dewetting transition in the presence of nanoscopic grooves etched on the boundaries. This approach permits to retain the essential supra-molecular details of fluid-solid interactions without surrendering -in fact boosting- the computational efficiency of continuum methods. The method is first validated against the Molecular Dynamics (MD) results of Cottin-Bizonne et al. [Nature Mater. 2, 237 (2003)] and then applied to more complex geometries, hardly accessible to MD simulations. The resulting analysis confirms that surface roughness and capillary effects can promote a sizeable reduction of the flow drag, with a substantial enhancement of the mass flow rates and slip-lengths, which can reach up to the micrometric range for highly hydrophobic surfaces.