Self-Propulsion by Capillary-Dominated Faraday Instabilities

毛细管主导的法拉第不稳定性的自推进

• 批准号: 2321357
• 负责人: Pedro Saenz
• 金额: $ 40万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-10-01 至 2026-09-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2321357&HistoricalAwards=false
• 关键词: Self; Propulsion; Capillary; Dominated; Faraday

Understanding the unsteady flows generated by the oscillations of an interfacial surface that separates a liquid from a gas is a broad research area with numerous practical applications, from the transport of particles to the mixing of chemicals. This research project aims to develop a mathematical framework for understanding, predicting, and harnessing the fluid flows and spontaneous movements produced by periodic interfacial waves, with particular emphasis on new effects that emerge in geometrically confined liquid-air systems driven into vertical oscillations at small amplitude, less than a few millimeters. For example, research efforts will aim to explain why waves that oscillate in place in a wide channel, start to translate spontaneously when the channel is narrow, and how this phenomenon can be exploited to realize a new type of fluid pump. Educational efforts will aim to train students to succeed in modern multi-disciplinary work and research environments, by coaching them in diverse scientific and soft skills, with emphasis on strong communication skills and proficiency in the art of scientific visualization. The communication and visualization efforts will be leveraged to promote diversity in STEM through a range of outreach events. Faraday waves emerge when a liquid layer is subjected to periodic vertical oscillations, initially forming a standing pattern that begins to exhibit erratic movement as the amplitude of the forcing increases. A relatively unexplored question of interest is whether the chaotic dynamics of Faraday waves can be harnessed to produce coherent motion. Previous attempts to demonstrate this possibility through spatial confinement of the waves have been scarce and primarily focused on large, gravity-dominated Faraday waves. For this research project, preliminary experiments demonstrated the existence of spontaneous symmetry-breaking in small, capillary-dominated Faraday waves confined within narrow annular channels, resulting in persistent wave motion due to meniscus and contact-line dynamics. By integrating theory, simulations, and experiments, the main objective of this project is to understand and rationalize this instability and explore how similar phenomena can lead to new self-propulsion dynamics for confined waves, slugs, and bubbles. The project will investigate the influence of wettability and contact-line dynamics, two-layer configurations, and explore a variety of mixing and transport applications involving complex flow networks and fluid pumps. Special attention will be given to elucidating the role of streaming flows. A unified theoretical framework based on Floquet theory will be developed to analyze the observed Faraday instabilities. Theoretical advancements will be informed and validated by in-house experiments and direct numerical simulations.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.

了解分离液体和气体的界面表面的振荡所产生的非定常流动是一个具有许多实际应用的广泛的研究领域，从颗粒的运输到化学品的混合。这一研究项目旨在开发一个数学框架，用于理解、预测和利用周期性界面波产生的流体流动和自发运动，特别是在几何约束的液体-空气系统中出现的新效应，这些新效应被驱动成小幅度、小于几毫米的垂直振荡。例如，研究工作将致力于解释为什么在宽通道中就地振荡的波在通道窄时开始自发平移，以及如何利用这种现象来实现一种新型的流体泵。教育工作的目标是训练学生在现代多学科工作和研究环境中取得成功，方法是指导他们掌握各种科学和软技能，重点是强大的沟通能力和科学可视化艺术的熟练程度。将利用交流和可视化努力，通过一系列外联活动，促进科技教育的多样性。当液层受到周期性的垂直振荡时，就会出现法拉第波，最初形成一种站立的模式，随着强迫的幅度增加，这种模式开始表现出不稳定的运动。一个相对未被探索的感兴趣的问题是，是否可以利用法拉第波的混沌动力学来产生相干运动。以前通过波的空间限制来证明这种可能性的尝试很少，主要集中在以重力为主的大型法拉第波上。在本研究项目中，初步实验证明，在狭窄的环形通道内，以毛细管为主的法拉第小波中存在自发的对称性破缺，导致由于半月面和接触线动力学而产生的持续波动。通过将理论、模拟和实验相结合，该项目的主要目标是了解这种不稳定性并使其合理化，并探索类似现象如何导致受限波、弹状物和气泡的新的自航动力学。该项目将研究润湿性和接触线动力学、两层结构的影响，并探索涉及复杂流动网络和流体泵的各种混合和运输应用。将特别注意阐明流动的作用。基于弗洛奎理论的统一理论框架将被用来分析观测到的法拉第不稳定性。理论上的进步将通过内部实验和直接的数值模拟来通知和验证。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。