CAREER: Surfactant impact on laminar drag reduction of realistically-textured superhydrophobic surfaces

职业：表面活性剂对真实纹理超疏水表面层流减阻的影响

• 批准号: 2048234
• 负责人: Paolo Luzzatto-Fegiz
• 金额: $ 50万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2048234&HistoricalAwards=false
• 关键词: CAREER; Surfactant; impact; laminar; drag

Drag-reducing coatings have been investigated to reduce the large pressure differences that can arise in microfluidic devices and in micro-cooling applications, as well as to enhance control in chemical or biological analysis. Superhydrophobic surfaces is a promising type of drag-reducing coating, which uses a combination of microscopic texture and hydrophobicity to retain a thin coating of air bubbles when submerged in a liquid, like water. However, surfactants, which are naturally present in the environment or in many working liquids, can drastically curtail the achievable drag reduction through a mechanism that is highly sensitive to the details of the coating texture. This project will use simulations, theory, and experiments to investigate drag reduction phenomenon in laminar flow microchannels with superhydrophobic surfaces in the presence of surfactants. The project will encompass several educational activities, including university course developments, an undergraduate research program, a hands-on activity for local junior high school outreach events, and a K-12 learning activity targeting the Next Generation Science Standards.This project aims to predict superhydrophobic drag reduction in laminar flow with surfactants, as a function of texture geometry, bulk flow properties, surfactant type and concentration. This will be achieved by examining superhydrophobic surfaces of progressively increasing complexity, using a combination of numerical simulations, theory, and experiments. The numerical simulations will enable precise control of surfactant properties and concentration and solve the equations for the transport of mass, momentum, and surfactant in the fluid interior and along the air–water interface. The results will be used to develop tractable theoretical models, which will yield insight about how flow properties and texture geometry affect the resulting drag. The theoretical models will also be used for rapid drag reduction predictions. In the experiments, superhydrophobic surfaces will be placed in a microfluidic system, and confocal microscopy will be used to measure velocity fields near the air-water interface. The experiments will validate the simulations and theory. This three-pronged computational, theoretical, and experimental investigation will advance our understanding of surfactant effects on drag using superhydrophobic surfaces in realistic laminar flow conditions and lead to reliable prediction and mitigate strategies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

已经研究了减阻涂层以减少在微流体装置和微冷却应用中可能出现的大的压力差，以及增强化学或生物分析中的控制。超疏水表面是一种很有前途的减阻涂层类型，它使用微观纹理和疏水性的组合，以在浸没在液体（如水）中时保留薄的气泡涂层。然而，天然存在于环境中或许多工作液体中的表面活性剂可以通过对涂层纹理的细节高度敏感的机制来大幅削减可实现的减阻。本计画将利用模拟、理论与实验研究表面活性剂存在下，超疏水表面在层流微通道中的减阻现象。该项目将包括几个教育活动，包括大学课程开发，本科生研究计划，当地初中外展活动的实践活动，以及针对下一代科学标准的K-12学习活动。该项目旨在预测表面活性剂层流中的超疏水减阻，作为纹理几何形状，整体流动特性，表面活性剂类型和浓度。这将通过研究逐渐增加的复杂性的超疏水表面，使用数值模拟，理论和实验的组合来实现。数值模拟将能够精确控制表面活性剂的性质和浓度，并求解流体内部和沿着空气-水界面的质量、动量和表面活性剂传输方程。结果将被用来开发易于处理的理论模型，这将产生洞察力如何流动特性和纹理几何形状影响所产生的阻力。理论模型也将用于快速减阻预测。在实验中，超疏水表面将被放置在微流体系统中，共聚焦显微镜将被用来测量空气-水界面附近的速度场。实验将验证模拟和理论。这三管齐下的计算，理论和实验研究将推进我们的表面活性剂对阻力的影响，使用超疏水表面在现实层流条件下的理解，并导致可靠的预测和减轻策略。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。