Drag reduction and antifouling of a spontaneous fast moving air film

Abstract

Minimizing frictional resistance and preventing the attachment of marine organisms are extremely important for global ship navigation to reduce energy consumption and carbon emissions. However, there is still a lack of an effective and environmentally-friendly drag reduction and antifouling method. Here, we propose a spontaneous fast-moving air film to resolve this problem. We first developed a serial brachistochrone-shaped superhydrophobic pattern to easily capture underwater air bubbles and realize the spontaneous and directional transportation of bubbles with an average velocity of 444 mm s⁻¹ that is the fastest in the whole world. Then, the continuous supply of air bubbles and serial brachistochrone-shaped superhydrophobic pattern were combined to form a spontaneous fast-moving air film, which not only prevents the escape of supplied air bubbles but also replenishes the air film on a superhydrophobic surface. The spontaneous fast-moving air film showed an amazing 27% drag reduction rate and simultaneous 80% antifouling rate, which was an outstanding capability that had never been reported before. This effective and environmentally-friendly drag reduction and antifouling method will minimize energy consumption and carbon emissions and has strong implications for global sustainable development.