Overflow Control for Sustainable Development by Superwetting Surface with Biomimetic Structure

Abstract

Liquid flowing around a solid edge, i.e., overflow, is a commonly observed flow behavior. Recent research into surface wetting properties and microstructure-controlled overflow behavior has attracted much attention. Achieving controllable macroscale liquid dynamics by manipulating the micro-nanoscale liquid overflow has stimulated diverse scientific interest and fostered widespread use in practical applications. In this review, we outline the evolution of overflow and present a critical survey of the mechanism of surface wetting properties and microstructure-controlled liquid overflow in multilength scales ranging from centimeter to micro and even nanoscale. We summarize the latest progress in utilizing the mechanisms to manipulate liquid overflow and achieve macroscale liquid dynamics and in emerging applications to manipulate overflow for sustainable development in various fields, along with challenges and perspectives.

Introduction to the biomimetic design of interfacial materials for water overflow control

“…1 In the case of dynamic interactions, the state of the solid-liquid interface is not only determined by the surface energy and micro-nano structures of the solid-liquid material itself, but also affected by other factors, such as liquid viscosity, inertia, laminar/ turbulent flow, and pressure change caused by the relative velocity at the interface between the fluid and the surrounding air, etc. 6 Insufficient research on the role of these factors limits the understanding and application of the solid-liquid interaction.…”

“…In recent years, with the development of super-wettable surface material technology, 1 the influence of surface wettability on overflow behavior has begun to receive renewed attention. 6 This feature article summarizes the current research studies of our research group on the control of overflow behavior in recent years from aspects including the bioinspired idea, the fabrication of superwettable surfaces, the development of control techniques, the concerns regarding the designed materials on the environment and health, an exploration of control mechanisms, etc., and provides an outlook of the accurate control of overflow by surfactant and additives, along with challenges and perspectives.…”

“…The necessary centripetal force could result from several different effects, such as the pressure drop across the liquid film and the capillary force. 6 Surface superwettabilities have provided a unique opportunity to control the dynamics of overflow behaviour at both high and low flow speeds. 7 Superhydrophobic structures were found to the greatly reduce the liquid–solid adhesion at low flow speeds and counteract the Coanda effect at high flow speeds.…”

“…Liquid overflow at solid edges may be commonly observed in situations of people dispensing, 9 pouring liquid from a nozzle 10 or bottle, 8 and people walking, 11 automobiles driving, or even aircrafts landing on the wet ground after raining, 13 where flowing liquids in a wide flow velocity range tend to flow over a curved surface and then separate at a certain point, sometimes leading to a dribble or a splash, which is normally undesirable. 6 Therefore, an in-depth understanding of the overflow phenomenon, especially the influence of the wettability of the solid surface on it, may have an important impact on these application fields. From the 1950s to 1990s, researchers proposed several controlling methods through experimental studies or theoretical calculations.…”

“…In recent years, with the development of super-wettable surface material technology, 1 the influence of surface wettability on overflow behavior has begun to receive renewed attention. 6…”