CBET-EPSRC: Surfactant impact on drag reduction of superhydrophobic surfaces in turbulent flows

CBET-EPSRC：表面活性剂对湍流中超疏水表面减阻的影响

• 批准号: EP/T030739/1
• 负责人: Oliver E Jensen
• 金额: $ 43.39万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FT030739%2F1
• 关键词: CBET; EPSRC; Surfactant; impact; drag

Superhydrophobic surfaces (SHS) are bio-inspired engineered surfaces or coatings with several surprising and useful properties. By trapping air inside micro cavities, SHS can prevent small amounts of liquid such as water droplets from spreading on the surface, leading to the well-known lotus-leaf effect. When immersed in water, SHS can reduce friction drag between the liquid and the surface, owing to the entrapped air layer. Drag reduction from SHS has the potential to substantially reduce energy use, gas emissions and costs in maritime transport, and numerous other applications in fluid dynamics and heat transfer. Following the 2018 meeting of the International Maritime Organisation, the UK decided to reach zero gas emissions in British maritime shipping by 2050. Drag reduction technologies such as SHS can significantly contribute towards achieving this important environmental goal, whilst providing new economic opportunities in green technologies.However, SHS have shown inconsistent performance when tested in the lab or in the field, in both laminar and turbulent flow conditions. Many results deviate significantly from theoretical and numerical predictions. Our recent experimental, numerical and theoretical work has revealed that trace amounts of surfactant can significantly impair the drag-reduction performance of SHS in laminar flows. Surfactants are naturally present in oceans and rivers, as well as most engineering applications. Their impact on SHS in turbulent flow conditions is presently unknown. Building on our recent work on laminar flows, we hypothesize that surfactant can also affect the performance of SHS in turbulent flows, explaining inconsistencies found in experimental tests and the mismatch with existing models, which currently all ignore surfactant.To investigate this hypothesis, our multi-national team, composed of experts in numerical simulation from the University of California Santa Barbara (US) and experts in theoretical modelling from the University of Manchester (UK), will perform the first ever fundamental modelling investigation of superhydrophobic drag reduction in turbulent flow with surfactant. We will implement fully-resolved numerical simulations of surfactant-inclusive turbulent flow above SHS, using special refinement techniques in order to reach flow regimes relevant to realistic conditions for maritime applications. In addition, simpler theoretical models will be developed to identify and predict key physical and surfactant processes. The theoretical models will give us the flexibility to explore rapidly the complex dynamics of how surfactant can affect SHS drag reduction in turbulent flows. The numerical simulations will provide a wealth of detailed information about the flow dynamics and the effect of surfactants, and will be used to validate our theoretical models.To increase the impact of our findings, highly resolved data from our numerical simulations and algorithms implementing our models will be made freely available online. This will allow researchers to readily exploit our results in order to optimize SHS designs and improve their performance even when surfactant is present. Our objective is to uncover the impact of surfactant in realistic conditions in order to identify practical mitigation strategies and unlock the drag-reduction potential of SHS for real-world applications.

超疏水表面（SHS）是一种受生物启发的工程表面或涂层，具有几种令人惊讶和有用的特性。通过将空气困在微腔内，SHS可以阻止水滴等少量液体在表面扩散，从而导致众所周知的荷叶效应。当SHS浸入水中时，由于被困空气层，SHS可以减少液体与表面之间的摩擦阻力。SHS的减阻有可能大幅减少海上运输中的能源使用、气体排放和成本，以及流体动力学和传热领域的许多其他应用。在2018年国际海事组织会议之后，英国决定到2050年实现英国海运零气体排放。像SHS这样的减阻技术可以为实现这一重要的环境目标做出重大贡献，同时为绿色技术提供新的经济机会。然而，无论是在实验室还是在现场，无论是在层流还是湍流条件下，SHS都表现出了不一致的性能。许多结果明显偏离理论和数值预测。我们最近的实验、数值和理论研究表明，微量表面活性剂会显著影响层流中SHS的减阻性能。表面活性剂天然存在于海洋和河流中，也存在于大多数工程应用中。它们对湍流条件下SHS的影响目前尚不清楚。基于我们最近对层流的研究，我们假设表面活性剂也可以影响湍流中SHS的性能，从而解释了实验测试中发现的不一致以及与现有模型的不匹配，目前这些模型都忽略了表面活性剂。为了研究这一假设，我们的多国团队，由来自加州大学圣巴巴拉分校（美国）的数值模拟专家和曼彻斯特大学（英国）的理论建模专家组成，将对表面活性剂在湍流中的超疏水减阻进行首次基础建模研究。我们将使用特殊的细化技术，对SHS上方含表面活性剂的湍流进行完全解析的数值模拟，以达到与海上应用实际条件相关的流动状态。此外，将开发更简单的理论模型来识别和预测关键的物理和表面活性剂过程。理论模型将使我们能够灵活地快速探索表面活性剂如何影响湍流中SHS减阻的复杂动力学。数值模拟将提供有关流动动力学和表面活性剂影响的丰富详细信息，并将用于验证我们的理论模型。为了增加我们发现的影响，我们的数值模拟和实现我们模型的算法的高分辨率数据将在网上免费提供。这将使研究人员能够很容易地利用我们的结果来优化SHS设计，并在存在表面活性剂的情况下提高其性能。我们的目标是揭示表面活性剂在现实条件下的影响，以确定实际的缓解策略，并在实际应用中释放SHS的减阻潜力。

项目成果

Confinement-induced drift in Marangoni-driven transport of surfactant: a Lagrangian perspective

马兰戈尼驱动的表面活性剂传输中约束引起的漂移：拉格朗日视角

• DOI: 10.48550/arxiv.2310.09559
• 发表时间: 2023
• 作者: Mcnair R

Unsteady evolution of slip and drag in surfactant-contaminated superhydrophobic channels

表面活性剂污染的超疏水通道中滑移和阻力的不稳定演化

• DOI: 10.48550/arxiv.2310.18184
• 发表时间: 2023
• 作者: Tomlinson S

SLIP AND DRAG IN TURBULENT FLOWS OVER SUPERHYDROPHOBIC SURFACES WITH SURFACTANT

含有表面活性剂的超疏水表面上的湍流中的滑移和阻力

• 发表时间: 2022
• 期刊: 12th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2022
• 作者: Tomlinson S.D.

A model for slip and drag in turbulent flows over superhydrophobic surfaces with surfactant

• DOI: 10.1016/j.ijheatfluidflow.2023.109171
• 发表时间: 2023-02
• 期刊: International Journal of Heat and Fluid Flow
• 影响因子: 2.6
• 作者: Samuel D. Tomlinson;Franccois J. Peaudecerf;Fernando Temprano-Coleto;F. Gibou;P. Luzzatto‐Fegiz;O. Jensen;J. Landel

Laminar drag reduction in surfactant-contaminated superhydrophobic channels

• DOI: 10.1017/jfm.2023.264
• 发表时间: 2022-09
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Samuel D. Tomlinson;F. Gibou;P. Luzzatto‐Fegiz;Fernando Temprano-Coleto;O. Jensen;J. Landel