Vorticities, Coherent Structures, and Surface Roughness Effect in Turbulent Thermal Convection

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This research uses laser light scattering and other modern experimental methods to study the shape and dynamics of the large-scale velocity structures, spatial and temporal correlations between the velocity and temperature fields, and the surface roughness effect on the heat transport in turbulent convection driven by a large temperature gradient across a fluid layer. The proposed experiments involve investigation of universal features of turbulence, such as intermittency, coherent structure, and anomalous scaling, and also include exploration and characterization of special behaviors of turbulent convection in a closed cell under different boundary conditions. Emphasis will be placed on the understanding of the dynamic process and the physical mechanism of the characteristic features of convective turbulence. The study of turbulent convection over a rough surface is directly related to the convection in the atmosphere and oceans, where the underlying surfaces are almost always rough. This research contains a combination of exploring new physics and instrumentation development. Students involved in the project will receive a broad training in physics and optics, which will prepare them for a range of careers in academe, industry or government. The development of a novel fiber-optic vorticity probe will provide a powerful tool, which can be used widely in the general area of fluid dynamics. %%%This work uses laser light scattering and other modern experimental techniques to study turbulent fluid motion driven by a large temperature gradient across a fluid layer. The proposed experiments involve investigation of the shape and dynamics of the large-scale velocity structures, spatial and temporal correlations between the velocity and temperature fields, and the surface roughness effect on the heat transport in turbulent thermal convection. These experiments are of fundamental interest for the physical understanding of convective turbulence, and they are also relevant to many practical applications. The study of turbulent convection over a rough surface is directly related to the convection in the atmosphere and oceans, where the underlying surfaces are almost always rough. Understanding the heat transport in turbulent convection will shed new light on technological improvements for more efficient heat transfer in various industrial applications ranging from heat exchangers to reentry vehicles in the space flight. This research contains a combination of exploring new physics and instrumentation development. Students involved in the project will receive a broad training in physics and optics, which will prepare them for a range of careers in academic or industrial science. The development of a novel fiber-optic vorticity probe will provide a powerful tool, which can be used widely in the general area of fluid dynamics.