A Numerical Study of Drag Reduction of Superhydrophobic Surfaces in Shipping Industry

As energy-conservation and emission-reduction become more and more severe, the concept of Green Ship has been proposed. And drag reduction is a realizable method to achieve this goal. Superhydrophobic surfaces (SHSs) whose contact angle is greater than 150 have attracted much attention because of the ability of realizing drag reduction in turbulent flows. However, few researchers focus on the application of SHSs in shipping industry. In this paper, a numerical study of turbulent channel flows and turbulent boundary layers developing over SHSs are performed. In the simulation, the VOF multiphase flow model is used for the gas-liquid phase flow, and a superhydrophobic surface microstructure grid with local encryption technology is adopted. The results show that within the range of ship economic speed, a stable gas vortex can form in the upper part of microstructure, and the drag reduction ratio of SHSs has a close relationship with size of velocity, gas-liquid contact area, and soaking time.