CAREER: A coupled multiscale study of phase change dynamics at curved liquid-vapor interfaces

职业：弯曲液-汽界面相变动力学的耦合多尺度研究

• 批准号: 2339757
• 负责人: Kishan Bellur
• 金额: $ 53.27万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-01 至 2029-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2339757&HistoricalAwards=false
• 关键词: CAREER; coupled; multiscale; study; phase

Liquid-vapor surfaces are ubiquitous in natural and engineered devices. A cup of coffee, a tree, and an air-conditioning unit, all have liquid-vapor interfaces and are undergoing “evaporation” in some form. Curved interfaces with contact lines (such as droplets, menisci, and thin films) exhibit unique properties due to surface tension that significantly alters evaporation/condensation. In turn, the evaporation/condensation moves the liquid-vapor interface. The intricate coupling between evaporation/condensation and interface dynamics becomes important when surface tension is the dominant force. However, this coupling is still not well understood. In the project, the dynamic stability of liquid-vapor interfaces is investigated using experiments coupled with modeling. The proposed work will advance fundamental understanding of phase change at curved liquid-vapor surfaces and enable the development of advanced technologies that involve thin films and contact lines. The application areas include manufacturing, boiling, porous media transport, electronics cooling, micro-scale heat transfer devices, decarbonization, hydrogen technology, and food-water-energy nexus. The PI will also establish an “edible science” outreach program at the local farmers market focused on thermo-fluid science in the kitchen. The outreach effort leverages the research co-op program at the University of Cincinnati to promote undergraduate research while encouraging domestic minority student involvement. In addition, data communication workshops will be developed to train students on “storytelling with data” for the upcoming data driven job market.Evaporating thin films are critical to the development of devices in a wide variety of industries. However, a complete understanding is still lacking, in part, due to the complex coupling between phase change and capillarity/wetting dynamics. A curved interface exhibits non-uniform phase change flux due to the existence of an adsorbed film. This film is in a metastable condition balanced by thermal and mechanical contributions to phase change. It is anticipated that a spatiotemporal mismatch of the thermal and mechanical effects at the nanoscale results in dynamic film oscillations, influences contact line motion, macroscale stability, and overall phase change heat transfer, and is a major contributor to the “stick-slip” phenomena. However, direct measurements of both the thermal and mechanical factors have not been made thus far due to the very small length scales involved. In this project, the dynamic phase change driven stability of the curved liquid-vapor interfaces is investigated through a unique combination of experiments and modeling. The novel experiment will simultaneously measure film thickness/curvature and wall temperature with high spatiotemporal resolution in a single dual-interferometry setup. This is complemented by a transient multiscale computational model consisting of a macroscale computational fluid dynamics submodel (10 μm), a microscale thin film submodel (10 μm) and a nanoscale molecular dynamics submodel (50 nm). Using a coupled approach, the influence of phase change driven (in)stability at the micro/nanoscale on macroscale contact line motion will be investigated. The project will enable a fundamental understanding of the appropriate boundary conditions and enable new insights into the complex coupling between multiple length scales.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.

液体-蒸汽表面在天然和工程设备中无处不在，一杯咖啡、一棵树和一台空调，都具有液体-蒸汽界面，并以某种形式经历着带有接触线的“蒸发”。由于表面张力显着改变蒸发/冷凝，液滴、弯月面和薄膜等表现出独特的性质，而蒸发/冷凝又使液-气界面移动。当表面张力是主导力时，蒸发/冷凝和界面动力学之间复杂的耦合变得很重要，但是，在该项目中，我们仍然没有很好地理解液-气界面的动态稳定性。拟议的工作将增进对弯曲液-气表面相变的基本理解，并促进涉及薄膜和接触线的先进技术的开发，应用领域包括制造、沸腾、多孔介质传输、电子冷却、微尺度热量。传输设备，脱碳、氢技术和食品-水-能源关系 PI 还将在当地农贸市场建立一个“食用科学”推广计划，重点关注厨房中的热流体科学。辛辛那提大学的研究项目旨在促进本科生研究，同时鼓励国内少数族裔学生参与。此外，还将举办数据通信研讨会，为即将到来的数据驱动的就业市场培训学生“用数据讲故事”。蒸发薄膜对于这一发展至关重要。广泛的设备然而，由于相变和毛细管/润湿动力学之间的复杂耦合，仍然缺乏完整的理解。由于吸附膜的存在，弯曲界面表现出不均匀的相变通量。薄膜处于亚稳态状态，由热和机械对相变的贡献来平衡，预计纳米尺度上的热和机械效应的时空失配会导致动态薄膜振荡，影响接触线运动、宏观稳定性和稳定性。总体相变传热，并且是“粘滑”现象的主要贡献者。然而，由于该项目涉及的长度尺度非常小，迄今为止尚未对热因素和机械因素进行直接测量。通过实验和建模的独特组合，研究了动态相变驱动的弯曲液-气界面的稳定性。该新颖的实验将在单个双干涉测量装置中以高时空分辨率同时测量薄膜厚度/曲率和壁温。补充为瞬态多尺度计算模型由宏观计算流体动力学子模型 (10 μm)、微观尺度薄膜子模型 (10 μm) 和纳米级分子动力学子模型 (50 nm) 组成，使用耦合方法，相变驱动的影响（该项目将研究宏观接触线运动在微/纳米尺度上的稳定性，并使人们能够对适当的边界条件有一个基本的了解，并对多个长度尺度之间的复杂耦合产生新的见解。该奖项反映了 NSF 的法定使命。通过使用基金会的智力优点和更广泛的影响审查标准进行评估，并被认为值得支持。