The Role of Interstitial Air Layer in Drop Impact on Liquid-infused Surfaces

间隙空气层在液体注入表面的液滴冲击中的作用

• 批准号: 1705745
• 负责人: Ying Sun
• 金额: $ 31.9万
• 依托单位: Drexel University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2022-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1705745&HistoricalAwards=false
• 关键词: Role; Interstitial; Air; Layer; Drop

Liquid-infused surfaces have attracted great interest in recent years due to their super slippery properties upon drop impact and potential benefits in self-cleaning and anti-fouling applications without much understanding of the underlying physics. The proposed project seeks to address this issue by examining the drop impact dynamics on lubricated and liquid-infused surfaces, with a focus on probing the role of the entrained air layer prior to drop-film contact and during drop-film interactions. Understanding the air film dynamics underneath the droplet allows for the better tuning of the liquid film properties in the lubricating layer, designing more robust nanostructures, and ultimately enhancing the performance of liquid-infused surfaces for applications ranging from anti-fouling and anti-icing to phase separation and thermal management. Since the air film dissipation is a universal phenomenon, the outcome of this study is also relevant to many industrial processes such as multilayered inkjet printing of functional materials, spray coating on wetted surfaces, combustion of fuel in internal combustion engines, pesticide spraying on waxy plant leaves as well as cooling of microelectronics. The project is hence relevant to several research frontiers of fluid mechanics in conjunction with surface sciences, nanomanufacturing, and heat transfer. This project will also enable new course materials for PI's two recently developed courses on Interfacial Transport Phenomena and Nanomanufacturing, as well as original contributions to the Gallery of Fluid Motion at the American Physical Society Division of Fluids Dynamics Meetings. In addition to training graduate students, the PI will actively mentor undergraduate researchers and recruit women and under-represented minority students. The community outreach programs extend to inner-city K-12 teachers and students through the Philly Materials Day, Philly Science Festival, and Drexel Graduate Fellows in K-12 and Research for Undergraduate programs.The key objective of this study is to advance the fundamental understanding of drop impact on lubricated and liquid-infused surfaces, with a focus on probing the role of the entrained air layer between the drop and film both prior to liquid-liquid contact and during liquid-liquid interaction. In contrast to drop impact on solid surfaces where even the smallest asperities cause random breakup of the entraining air film, the air film failure mechanisms on lubricated surfaces are expected to be much more controllable. Moreover, the post-rupture liquid-liquid contact may lead to interfacial instability and microbubble formation whose mechanisms are unclear. By integrating the total internal reflection microscopy, reflection interference microscopy, and high-speed imaging, the air film evolution and post-rupture liquid-liquid contact dynamics will be directly visualized for different impact conditions and drop/film/substrate properties with nanometer spatial and microsecond temporal resolution. This unique capability enables direct probing of air film profile at thickness where the liquid-liquid intermolecular interactions become important. The knowledge obtained from this project will bridge the gap between the drop impact physics of solid surfaces to deep liquid pools and enable technological discoveries from surface structural design to enhanced lubricant stability. The specific project aims are to address the following issues as fundamental to drop impact on lubricated and liquid-infused surfaces: (1) How does the air film evolve and rupture with varying impact conditions, film properties, and ambient pressure? (2) What is the frontal growth dynamics of liquid-liquid contact after air film ruptures? (3) What is the mechanism of finger-like instability at the growing liquid-liquid front? (4) How do surface structures and inclination affect air entrainment and drop impact dynamics?

近年来，液体注入表面因其在跌落冲击时的超滑特性以及在自清洁和防污应用中的潜在优势而引起了人们的极大兴趣，而无需对基础物理有太多了解。拟议的项目旨在通过检查润滑和液体注入表面上的液滴冲击动力学来解决这个问题，重点是探讨滴膜接触之前和滴膜相互作用期间夹带空气层的作用。了解液滴下方的空气膜动力学可以更好地调节润滑层中的液膜特性，设计更坚固的纳米结构，并最终增强液体注入表面的性能，适用于从防污、防冰到防污等各种应用。相分离和热管理。由于气膜耗散是一种普遍现象，因此这项研究的结果也与许多工业过程相关，例如功能材料的多层喷墨印刷、润湿表面的喷涂、内燃机中燃料的燃烧、蜡质植物上的农药喷洒叶子以及微电子设备的冷却。因此，该项目与流体力学、表面科学、纳米制造和传热等多个研究前沿相关。该项目还将为 PI 最近开发的两门关于界面传输现象和纳米制造的课程提供新的课程材料，并为美国物理学会流体动力学会议部门的流体运动画廊提供原创贡献。除了培训研究生外，PI还将积极指导本科生研究人员并招募女性和代表性不足的少数族裔学生。社区外展计划通过费城材料日、费城科学节以及 K-12 研究生和本科生项目研究扩展到市中心的 K-12 教师和学生。这项研究的主要目标是推进基本的了解液滴对润滑和液体注入表面的影响，重点是探讨液-液接触之前和液-液相互作用期间液滴和薄膜之间夹带空气层的作用。与固体表面上的跌落冲击相比，即使是最小的粗糙度也会导致夹带气膜的随机破裂，而润滑表面上的气膜失效机制预计会更加可控。此外，破裂后液-液接触可能导致界面不稳定和微泡形成，其机制尚不清楚。通过集成全内反射显微镜、反射干涉显微镜和高速成像，可以直接可视化不同冲击条件和纳米空间和液滴/薄膜/基材特性的气膜演化和破裂后液-液接触动力学。微秒时间分辨率。这种独特的功能可以直接探测液-液分子间相互作用变得重要的厚度处的空气膜轮廓。从该项目中获得的知识将弥合固体表面的跌落冲击物理与深层液池之间的差距，并实现从表面结构设计到增强润滑剂稳定性的技术发现。该项目的具体目标是解决以下问题，作为降低润滑和液体注入表面冲击力的根本问题：（1）随着冲击条件、薄膜特性和环境压力的变化，气膜如何演变和破裂？ （2）气膜破裂后液-液接触的锋面增长动力学是怎样的？ (3)液-液前沿不断增长的指状不稳定性的机制是什么？ (4) 表面结构和倾斜度如何影响空气夹带和跌落冲击动力学？

项目成果

Air film contact modes of drop impact on lubricated surfaces under reduced pressures

减压下液滴冲击润滑表面的气膜接触模式

• DOI: 10.1063/5.0065747
• 发表时间: 2021
• 期刊: Physics of Fluids
• 影响因子: 4.6
• 作者: Zhang, Lige;Soori, Tejaswi;Rokoni, Arif;Kaminski, Allison;Sun, Ying
• 通讯作者: Sun, Ying

Learning new physical descriptors from reduced-order analysis of bubble dynamics in boiling heat transfer

从沸腾传热中气泡动力学的降阶分析中学习新的物理描述符

• DOI: 10.1016/j.ijheatmasstransfer.2021.122501
• 发表时间: 2022
• 期刊: International Journal of Heat and Mass Transfer
• 影响因子: 5.2
• 作者: Rokoni, Arif;Zhang, Lige;Soori, Tejaswi;Hu, Han;Wu, Teresa;Sun, Ying
• 通讯作者: Sun, Ying

Thin film instability driven dimple mode of air film failure during drop impact on smooth surfaces

• DOI: 10.1103/physrevfluids.6.044002
• 发表时间: 2021-04
• 作者: Lige Zhang;Tejaswi Soori;Arif Rokoni;Allison Kaminski;Ying Sun

The effect of particle wettability on the stick-slip motion of the contact line

• DOI: 10.1039/c8sm02129e
• 发表时间: 2018-12-21
• 期刊: SOFT MATTER
• 影响因子: 3.4
• 作者: Kim, Dong-Ook;Pack, Min;Sun, Ying
• 通讯作者: Sun, Ying