Abstract: The two-dimensional fluid flow in superhydrophobic microchannels with transverse grooves was numerically simulated with Fluent to investigate the impact of the liquid-gas interface curvature on the effective slip behavior in the laminar regime. The effects of shear-free fraction, normalized periodic cell length and Reynolds number on the normalized slip length and pressure drop reduction are also examined. The results show that as protrusion angle increases, the normalized slip length and pressure drop reduction exhibit with single-hump variations. When θ=θ_opt, increments in the normalized slip length and pressure drop reduction tend to be greater as shear-free fraction and normalized periodic cell length decrease, leading to the better drag reduction effect. When θ?θ_n, especially θ?90°, the transverse grooves deteriorate flow resistance, and the normalized slip length and pressure drop reduction decrease significantly with increasing shear-free fraction and normalized periodic cell length. The effect of Reynolds number on drag reduction is approximately negligible.

Key words: superhydrophobic surfaces, microchannels, numerical simulation, gas-liquid interface curvature