Sustainable Drag Reduction of Fatty Acid Amide‐Based Oleogel Surface Under High‐Speed Shear Flows

Abstract

Nepenthes alata-inspired micro/nano-textured lubricant-infused surface (LIS) has shown strong potential in the fields of drag reduction (DR), anti-biofouling, and self-cleaning. However, its surface-slippery property is largely degraded under turbulent shear flow conditions due to the loss of the impregnated oil. This condition inhibits its practical applications to marine vehicles. The mucus-impregnated tissue systems of marine creatures are primarily based on fatty acid amides (FAAs), such as erucamide or oleamide, which have been commercially utilized as solid-slip additives. A stable lubricant interface of erucamide-PDMS composite (EPC) oleogel is formed by cross-linking erucamide with PDMS gel network prior to infusion of silicon oil. In this study, the surface stability and lubricant retention of EPC are investigated in consideration of DR applications. The fabricated EPC-oleogel surface exhibits shear stable DR under harsh conditions, such as high pressure, temperature, and shear flow conditions. The surface shows a shear stable DR performance of about 14% even up to a high-speed flow of 12 ms−1, corresponding to friction Reynolds number (Reτ) of approximately 5000. The superior lubrication stability of FAA-oleogel at the flow conditions of cruising ships ensures its strong potential for sustainable fuel economy of marine vehicles.