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Turbulence dans l'espace de Fourier: mesures de vorticité par diffusion acoustique

Abstract : In this thesis, we deal with experimental measurements of vorticity in Fourier space by using acoustic scattering technique. Measurements have been performed on the one hand in a laboratory air jet, and on the other one in a gazeous 4 Kelvin Helium jet located at CERN (Geneva) thus enabling to cover a wide range of Taylor based Reynolds numbers (400-6000).We get the data acquisition system features by means of controlled experiments, as well as acoustic numerical calculations. That allows a comprehensive undertanding of diffraction effects involved in a scattering experiment with finite size transducers. Study of decorrelation of a Fourier mode reveals two characteristic times governing the vorticity “objects” dynamic : a short one proportional to the sweeping time, and a large one proportional to the integral time. Interferometry coupled with time-frequency analysis show that the large spectral time can be associated with non-local interactions whereas the short one depicts the local ones. Finally, we show that Fourier modes exhibit a strong intermittency, growing with increasing Reynolds and wave numbers. Laboratoire des ´ecoulements geophysiques et industriels LEGI BP53, 38041 Grenoble Cedex 9
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Contributor : Cedric Poulain <>
Submitted on : Wednesday, November 24, 2004 - 3:30:30 PM
Last modification on : Thursday, November 19, 2020 - 3:54:10 PM
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  • HAL Id : tel-00007506, version 1

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Cédric Poulain. Turbulence dans l'espace de Fourier: mesures de vorticité par diffusion acoustique. Acoustique [physics.class-ph]. Université Joseph-Fourier - Grenoble I, 2003. Français. ⟨tel-00007506⟩

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