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. ***
