Optimized sprayable marine creature inspired surface for effectual drag reduction under harsh condition

Nature-inspired slippery liquid-infused porous surface (SLIPS) has gained significant attention due to its wide range of applications, including antifouling, self-cleaning, and drag reduction. Drag reduction is particularly crucial in marine environments, as it helps reduce fuel consumption, leading to both economic and environmental benefits. However, SLIPS often lose its slippery features due to the easy depletion of the impregnated lubricant oil, primarily owing to external forces such as flow-induced shear stress. In this study, a sprayable marine creature inspired surface (sMIS) was fabricated to investigate the shear-induced depletion of the infused lubricant from cavities when it was exposed to highly turbulent flows in a water channel. The porosity of the sMIS surfaces is formed to play a key role in maintaining slipperiness by effectively retaining the infused lubricant inside the cavities. The porosity of the sMIS coating was optimized by varying polystyrene concentration and relative humidity by adopting the Taguchi method. The optimized sMIS coating surface (OMIS) retained its excellent slippery properties even after exposing to harsh conditions, including high-speed centrifugal forces. It demonstrated superior slippery performance compared to the non-optimized MIS and bare polydimethylsiloxane (PDMS) surfaces. OMIS surface also exhibited lower pressure drop and friction factor compared to bare surface. Conclusively, the developed OMIS coating surface has great potential in sustainable drag reduction applications.