Spatially heterogeneous superwettability in groove surfaces: Anchored plastron for underwater drag reduction
Year: 2026
Type: article
Abstract: The air layer, known as a plastron, on superhydrophobic surfaces plays a crucial role in underwater drag reduction. However, stabilizing the plastron in complex turbulent flow conditions is a significant challenge, which impairs its effectiveness in drag reduction. This study proposes a streamwise groove structure with heterogeneous superwettability (HS-groove). The surface of the groove is treated through alkaline etching and water bath processes to form micro-needle-like crystals, resulting in superhydrophilicity with a water contact angle (CA) near 0° on the top surface. The interior of the groove is modified with hexadecyltrimethoxysilane (HDTMOS), imparting superhydrophobicity, with a CA exceeding 160° and a water roll-off angle of approximately 2°. This HS-groove structure demonstrates superior underwater plastron stability and drag reduction performance compared to traditional superhydrophobic grooves. Under continuous water flow, the plastron within grooves exhibited long-term persistence, with the maximum duration reaching 7.3 h and the corresponding drag reduction rates ranging from 17.2% to 46.4% in the pipeline. The strong surface energy barrier of the HS-groove enables effective plastron retention, leading to drag reduction performance superior to that of pure superhydrophobic grooves. This study offers novel insights and potential applications in underwater drag reduction technologies.
Source: Ocean
Institutions: State Key Laboratory of Tribology, Tsinghua University
Language: English
Subfield: Surfaces, Coatings and Films
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Awards: G7753881274, G7821668069
OpenAlex ID: W7160488184
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