Two-Dimensional Hydrodynamics in Freely Suspended Films

9731701吴建议的研究旨在了解自由悬浮液膜中的流体流动和不稳定性，这些液膜的行为类似于二维(2D)流体。从历史上看，2D流体动力学一直是一个广泛的理论研究课题。然而，受控的实验室实验一直很少见。这个项目就是缩小这一差距的努力。这项研究将探索2D流动的不同方面，从对单个涡旋的研究到一系列相互作用强烈的涡流。将研究自由演化湍流的普遍衰变规律以及力湍流中的逆能量级联。这些实验将使用激光光散射、激光多普勒测速和真实空间成像进行。为了补充流体力学研究，还将做出新的努力来表征自由悬浮膜的物理性质。这包括对油膜粘度的研究，它与油膜结构的关系，以及油膜厚度与流场的动态耦合。该项目包括利用最先进的研究设施对研究生和本科生进行新项目的培训。项目主任还积极参与外联活动，如为科学博物馆制作大型肥皂片演示。自由悬浮液膜具有许多独特而迷人的特性。当薄膜厚度仅为其他尺寸的1/10,000时，薄膜的行为类似于二维(2D0)流体。例如，如果在胶片中产生流动，则速度限制在胶片平面内，垂直于胶片平面的速度变化可以忽略不计。这项研究的目的是了解二维内的流体流动和湍流。从历史上看，2D流体动力学一直被理论和计算机模拟所主导。然而，这个主题与许多自然发生的现象有关，如海洋和大气湍流、气旋和反气旋的形成。该项目涉及开发新技术，以制备坚固的薄膜，并通过最先进的激光散射和视频成像对其中的湍流进行监测。这些方法将揭示涡旋之间的相互作用，以及背景湍流海洋中大型相干涡旋的出现。这一研究结果将有助于湍流的理论模拟和进一步了解强非线性动力系统。该项目包括利用最先进的研究设施对研究生和本科生进行新项目的培训。项目主任还积极参与外联活动，如为科学博物馆制作大型肥皂片演示。***

9731701 Wu The proposed research is aimed at understanding fluid flow and instabilities in freely suspended liquid films that behave like a two-dimensional (2D) fluid. Historically, 2D hydrodynamics has been a subject of extensive theoretical investigation. However, controlled laboratory experiments have been rare. This project is an effort to narrow this gap. The research will probe different aspects of 2D flows, ranging from studies of individual vortices to an array of vortices that are strongly interacting. Universal decay laws of freely evolving turbulence as well as inverse energy cascades in force turbulence will be investigated. The experiments will be carried out using laser light scattering, laser Doppler velocimetry, and real-space imaging. To complement the hydrodynamic studies, new efforts will also be made to characterize physical properties of the freely suspended films. This includes the study of the film viscosity, its relationship to the structure of the films, and the dynamic coupling between film thickness and the flow field. The project involves training of graduate and undergraduate students in novel projects with state-of-the-art research facilities. The project director has also been active in outreach activities such a development of large scale soap film demonstrations for science museums. %%% A freely suspended liquid film has many unique and fascinating properties. With the film thickness being only 1/10,000 of its other dimensions, the film behaves like a two-dimensional (2D0 fluid. For example, if a flow is created in the film, the velocity is confined to the film plane with negligible velocity variations perpendicular to it. The proposed research is aimed at understanding fluid flow and turbulence in 2D. Historically, 2D hydrodynamics has been dominated by theory and computer simulations. However, the subject is relevant to many naturally occurring phenomena such as ocean and atmospheric turbulence, formation of cyclones and anticyclones. This project involves the development of novel techniques that allow preparation of robust films and which allow turbulence in them to be monitored via state-of-the art laser light scattering and video imaging. These methods will reveal interactions between vortices and the emergence of large coherent eddies in the sea of background turbulence. Results from this research will be beneficial to theoretical modeling of turbulence and in furthering understanding of strongly non-linear dynamic systems. The project involves training of graduate and undergraduate students in novel projects with state-of-the-art research facilities. The project director has also been active in outreach activities such a development of large scale soap film demonstrations for science museums. ***