Multi-functional mucus coated surfaces inspired by loach skin

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Ridge 구조를 가진 초소수성 표면에서 나노 구조가 공기층과 항력감소에 미치는 효과 연구

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Drag reduction of mucus infused surface inspired by kelp

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Effects of surface air injection on the air stability of superhydrophobic surface under partial replenishment of plastron

Frictional drag reduction using a superhydrophobic (SHPo) surface has attracted great attention due to its potential for practical application. Air plastron (i.e., pockets) trapped between structures in a submerged SHPo surface serves a crucial role in the drag reduction effect. However, the air plastron on the SHPo surface can easily be depleted by various factors, resulting in the deterioration of the drag reduction performance. This study proposed a surface air injection method to resolve the depletion problem and explored its effect on the enhancement of the air stability of the SHPo surface as a controllable strategy under partial replenishment conditions in which the replenishment rate is less than the depletion rate. An air injection layer is added to a ridged multi-layered SHPo (ML-SHPo) surface to supply air through the surface. The dynamic behavior of air plastron on the surface is directly visualized by an x-ray imaging technique. The temporal evolution of depletion length on the ridged ML-SHPo surface is monitored under laminar flows to understand the underlying basic physics of the enhanced air stability caused by surface air injection. The depletion rate of air plastrons on SHPo surfaces depended on the nondimensional air injection rate (C q). The dynamic behavior in the air depletion regime is closely associated with flow condition and C q. The stability of air plastrons is enhanced by 12%-87% as the C q value increases. In addition, a simple scaling relationship between the depletion rate and C q is proposed to predict the depletion rate of air plastrons (longevity) on ridged SHPo surfaces. © 2022 Author(s).11Nsciescopu

공기층 수명 향상을 위한 다층 초소수성 표면 연구

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Effects of mucous layer of slippery seaweed drag reduction

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Effects of surface morphological structure of a brown alga miyeok (Undaria pinnatifida) on sustainable drag reduction

Liquid-infused surfaces are a promising passive technique for frictional drag reduction. However, their practical application is limited by the easy depletion of the lubricant infused in the surface by external forces. Miyeok contains mucus on its surface, which induces a sustainable slippery surface under flow conditions. In this study, the effect of the surface morphological structures of miyeok on slippery characteristics was examined. The surface of miyeok has bump-like microstructures and tiny pores of mucilage gland cells with a re-entrant inlet configuration. A replica model of the miyeok surface was fabricated by adopting a molding process using polydimethylsiloxane. The miyeok replica model was dipped into a silicone oil solution to obtain a slippery surface property. The surface structures of fresh miyeok and the replica were checked by comparing their scanning electron microscopy images. A replica of a kelp surface was also fabricated by employing the same method. The heights of the surface microstructures of the miyeok replica were more uniform than those of the kelp replica. The sustainable drag reduction effect of the replica models' surfaces was assessed by a sessile drop method. The liquid-infused miyeok replica surface (LIMRS) showed better sustainability than other surfaces. The slippery properties of the LIMRS were examined by measuring slip length and pressure drop. The drag reduction rates measured by the two methods were approximately 24% and 19%. The present results would be helpful for understanding the effects of the surface structure of natural miyeok on sustainable drag reduction and developing a biomimetic sustainable drag-reducing surface.11Ysciescopu

미역의 형태학적 표면 구조가 지속가능한 항력감소에 미치는 효과 연구

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지속 가능한 항력 저감을 위한 해조류 미역의 형태학적 미끄럼 구조

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