Two-Dimensional Hydrodynamics in Freely Suspended Films

9731701吴提出的研究旨在了解流体流动和不稳定性的自由悬浮液体膜，其行为就像一个二维（2D）流体。从历史上看，二维流体力学一直是一个广泛的理论研究课题。然而，控制的实验室实验很少。这个项目就是为了缩小这一差距。这项研究将探索二维流动的不同方面，从单个漩涡的研究到强相互作用的漩涡阵列。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。实验将使用激光散射、激光多普勒测速和实时空间成像进行。为了补充流体动力学研究，还将作出新的努力来表征自由悬浮膜的物理性质。这包括对膜粘度的研究，它与膜结构的关系，以及膜厚度与流场之间的动态耦合。该项目包括用最先进的研究设施培训研究生和本科生的新项目。项目主任还积极参与外联活动，如为科学博物馆开发大型肥皂电影示范。自由悬浮的液体薄膜具有许多独特而迷人的特性。由于薄膜厚度仅为其他尺寸的万分之一，因此薄膜的行为类似于二维（2D0）流体。例如，如果流是在薄膜中产生的，速度被限制在薄膜平面上，垂直于它的速度变化可以忽略不计。所提出的研究旨在了解二维流体流动和湍流。从历史上看，二维流体力学一直被理论和计算机模拟所主导。然而，这门学科与许多自然现象有关，如海洋和大气湍流、气旋和反气旋的形成。该项目涉及新技术的开发，该技术可以制备坚固的薄膜，并可以通过最先进的激光散射和视频成像来监测其中的湍流。这些方法将揭示涡旋之间的相互作用和背景湍流中出现的大型连贯涡流。这一研究结果将有助于湍流的理论建模和对强非线性动力系统的进一步理解。该项目包括用最先进的研究设施培训研究生和本科生的新项目。项目主任还积极参与外联活动，如为科学博物馆开发大型肥皂电影示范。* * *

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. ***