This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.The superhydrophobicity of a microchannel is determined by not only the wettability of channel wall but also the surface topography. Recent experiments have found that superhrydrophobic surfaces can be achieved by pattering roughness on hydrophobic surfaces. In this paper, the dynamics of two-phase flow in microchannel with different wettability and topography is studied numerically by the lattice Boltzmann method (LBM). The mechanism of drag reduction resulted from the superhydrophobicity is investigated. In
particular, the effect of different rough surfaces on superhydrophobicity is analyzed. It is found that flow behaviours are strongly affected by the wall wettability and topography. The results show that the LBM has a good application prospect in the study of drag reduction in microchannels.The UK Royal Society-NSFC (China) International Joint Project (2009-2011), China NSFC under grant (50920105504), and China Scholarship Council (CSC)
