Additive Manufactured, Bioinspired Stainless Steel Surface for Robust Drag Reduction

Bioinspired superhydrophobic surfaces have been used for drag reduction. However, the secondary structures and the air cushions on these surfaces could be destructed in a flow, losing the effect of drag reduction. Here, a stainless-steel surface with mushroom-like cross-section (SMC) and diamond cavities (SMC D ) having a drag reduction rate up to 19.37% is developed by 3D printing. The concealed re-entrant structures in SMC D prevent the infiltration of water into the chamber and form gas cushions, which converts the sliding friction at liquid-solid interface into rolling friction at liquid-gas interface, realizing the drag reduction. Meanwhile, 98.3% of air can be maintained in the chamber in a flow with Reynolds number ( Re ) of 9 × 10 5 , ensuring the drag reduction in a high-velocity flow. Moreover, the continuous top stainless-steel surface and the supporting mesh network protect the critical re-entrant structures, ensuring the robustness of SMC. With the bioinspired design and one-step additive manufacturing process, SMC holds great potential for large-area production and applications requiring robust drag reduction.