Exploring Flow Structures in a 2D Fluid

该项目涉及流体湍流，这是一个重要的，长期存在的问题，在很大程度上仍未解决。 一个主要的困难是存在大量的自由度，强烈相互作用的流体。 所提出的研究试图通过研究二维几何结构中的湍流来简化问题，其中每个流体元素的运动可以使用快速视频成像系统在很长一段时间内进行跟踪。二维流体运动是在一个自由悬浮的薄液膜中实现的，几微米厚，并由电磁场驱动。研究将集中在流体动力学相干结构的相互作用和稳定性，如流动中的旋涡和鞍点。 据信，这些相干结构负责湍流中的能量和角动量传递。 实验结果将与对二维湍流中的旋涡和鞍形分布进行定量预测的统计模型进行比较。随着对二维湍流行为的更好理解，该研究可以为三维湍流的更困难问题提供新的见解，这不仅与物理学有关，而且与工程和气象学有关。 这项研究将涉及研究生和本科生在一个动态的环境中，研究和教育齐头并进。 参与这项研究的学生使用最先进的设备来研究一个迷人的和相关的基本物理系统，为他们未来的挑战做好准备，并为学术界，工业界和政府工作人员做好准备。流体湍流是一种复杂的现象，影响着科学和工程的所有部分。 这一现象的复杂性最好地反映在我们预测财富模式的能力有限上，尽管近年来计算能力有了巨大的提高。 这项工作旨在了解二维空间中的湍流，其中复杂性显着降低，但仍保留了三维湍流的最重要成分，即，强交互性和非决定性。 为了实现二维流动，使用厚度约为几微米的自由悬浮的液体薄膜，并由电磁场驱动。 使用最先进的视频成像系统，将在延长的时间段内跟踪每个流体元素的膜中湍流的演变。研究的重点是了解流体动力学旋涡如何相互作用，以及它们在不同流动条件下的稳定性。 新获得的见解将有助于我们理解更困难的三维湍流现象。 流动的液膜不仅对科学研究有价值，它也是各级物理教学的极好实验室。 参加这项工作的学生，研究生和本科生将接受基础科学（物理学），现代成像处理技术和计算机编程的严格培训。 这使他们在未来的职业生涯中，工业或政府。

The project deals with fluid turbulence, a significant, long-standing problem that remains largely unsolved. A major difficulty is the presence of a large number of degrees of freedom that are strongly interacting in a fluid. The proposed research attempts to simplify the problem by studying turbulence in a two-dimensional geometry in which motion of each fluid element can be followed over a long period of time using a fast video imaging system. Two-dimensional fluid motion is realized in a freely suspended thin liquid film, a few microns thick, and driven by an electromagnetic field. The research will focus on interaction and stability of hydrodynamic coherent structures, such as vortices and saddle points in the flow. It is believed that these coherent structures are responsible for energy and angular momentum transfer in turbulence. The experimental results will be compared with statistical models that make quantitative predictions about distributions of vortices and saddles in two-dimensional turbulence. With a better understanding of how two-dimensional turbulence behaves, the research can shed new light on more difficult problems of three-dimensional turbulence, which is relevant not only to physics but also to engineering and meteorology. The research will involve both graduate and undergraduate students in a dynamic environment where research and education go hand in hand. The students participating in this research use state-of-the-art equipment to study a fundamental physical system that is fascinating and relevant, preparing them for future challenges, and for the academic, industry, and government workforce.Fluid turbulence is a complex phenomenon, affecting all sections of science and engineering. The complexity of the phenomenon is best reflected in our limited ability to predict wealth patterns, despite dramatic improvements in the computational power in recent years. This work is aimed at understanding turbulence in a two-dimensional space, where the complexity is significantly reduced but yet still retains the most important ingredients of three-dimensional turbulence, i.e., strong interaction and non-determinism. To achieve two-dimensional flow, a thin freely suspended liquid film, about a few microns in thickness, is used and is driven by an electromagnetic field. Using a state-of-the-art video imaging system, the evolution of turbulence in the film will be followed for each fluid element for an extended period of time. The focus of the research is to understand how hydrodynamic vortices interact with each other and how stable they are under different flow conditions. The newly gained insight would help us to understand more difficult three-dimensional turbulent phenomenon. A flowing liquid film is not only valuable for scientific research; it is also a wonderful laboratory for teaching physics at all levels. Students, graduates and undergraduates who participate in this work, will receive rigorous training in fundamental science (physics), modern imaging processing techniques, and computer programming. This makes them well rounded for a future career in academe, industry or government.