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ISS: Gravitational Effects on the Faraday Instability

国际空间站：重力对法拉第不稳定性的影响

基本信息

批准号：
2025117
负责人：
Ranga Narayanan
金额：
$ 53.27万
依托单位：
University of Florida
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2025117&HistoricalAwards=false
关键词：
ISS Gravitational Effects Faraday Instability

项目摘要

When two immiscible liquids are subject to an oscillating mechanical field that is applied perpendicular to their interface an instability may arise. This instability is manifested by the sudden generation of waves and fluid motion at the interface and is termed the Faraday instability. The effect of gravity on vibration-induced instability at the interface between liquid bilayers will be investigated. Experiments performed on the International Space Station will test theories about the onset of the Faraday instability and its associated flow patterns. This study will be the first attempt to utilize the unique environment of microgravity to obtain information on the Faraday instability problem. Addressing this question could impact important processes here on Earth, including microfluidic mixing in bio-separations, microscale heat transfer, additive manufacturing, atomization-fuel injection, and patterned substrate development. The project involves graduate and undergraduate students working with space-implementation partner engineers. The project also involves both high school and middle school students from rural schools through summer science programs, in-class demonstrations, hands-on experiments, and live displays of microgravity experiments.The Faraday instability arises from resonance between the applied frequency of shaking and the natural frequency of a liquid system with an interface. The morphological patterns of the interface are dominated by gravity and insensitive to interfacial tension. It is hypothesized that, when gravity is absent, the length scales of the instability are much smaller than under Earth’s gravity bringing out the dominant effect of interfacial tension. This, in turn, ought to cause the interface to rupture in the absence of gravity for small frequencies, but not for high frequencies. This research project seeks to validate models for Faraday instability with defining experiments conducted in the absence of gravity on the International Space Station, comparing these to ground experiments. The project also seeks to determine when the interface saturates to standing waves and when it breaks catastrophically to rupture. Experiments involve direct imaging under frequency and amplitude control while the theory involves Floquet and nonlinear analyses that employ high fidelity spectral methods. Validation of models by irrefutable evidence gathered under a well-controlled, unique microgravity environment have the potential to be translatable to other important fields such as acoustic, electrostatic, and magnetic levitation and forcing of fluid interfaces.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.

当两种不混溶的液体受到垂直于其界面施加的振荡机械场时，可能会出现不稳定性。这种不稳定性表现为在界面处突然产生波和流体运动，并被称为法拉第不稳定性。本文将研究重力对双层液体界面振动诱导不稳定性的影响。在国际空间站上进行的实验将测试有关法拉第不稳定性及其相关流动模式的理论。这项研究将是利用微重力这一独特环境获取关于法拉第不稳定性问题的信息的第一次尝试。解决这个问题可能会影响地球上的重要过程，包括生物分离中的微流体混合，微尺度传热，增材制造，雾化燃料喷射和图案化基底开发。该项目涉及研究生和本科生与空间实施伙伴工程师合作。该项目还邀请来自农村地区的高中生和中学生参加，通过暑期科学课程、课堂演示、动手实验和微重力实验的现场展示。法拉第不稳定性是由振动频率与具有界面的液体系统的固有频率之间的共振引起的。界面的形态模式由重力控制，对界面张力不敏感。据推测，当重力不存在时，不稳定性的长度尺度比地球重力下小得多，从而产生界面张力的主导效应。反过来，这应该会导致界面破裂，在没有重力的情况下，对于小频率，但不是高频。该研究项目旨在通过在国际空间站上没有重力的情况下进行的定义实验来验证法拉第不稳定性模型，并将这些实验与地面实验进行比较。该项目还试图确定界面何时饱和到驻波，以及何时发生灾难性破裂。实验涉及频率和振幅控制下的直接成像，而理论涉及Floquet和非线性分析，采用高保真度的频谱方法。通过在良好控制的、独特的微重力环境下收集的无可辩驳的证据对模型进行验证，有可能被转化为其他重要领域，如声学、静电和磁悬浮以及流体界面的受力。该奖项反映了NSF的法定使命，并被认为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来支持。