Abstract: Numerical simulation on superhydrophobic surface of turbulent flow is shown. Velocity or shear stress of turbulent flow are provided and basic law between microscopic structure and drag reduction rate is analyzed. In simulation, we use an unsteady Reynolds averaged simulation model and VOF model for gas-liquid two phase flow. It shows that slip flow and cyclical shear stress exist on superhydrophobic surface. It can reduce resistance and increased resistance as well. Microstructure size has significant effect on drag reduction rate. In order to increase drag reduction rate, the aspect ratio of rectangular mierostructure should be greater than 3:2 and the groove spacing should be small, while the groove width should be less than 200 micron.

Key words: turbulent flow, superhydrophobic, drag reduction, micro-structured