Dynamique spatio-temporelle du champ de vorticité en turbulence : mesures par corrélation acoustique dynamique.

Abstract : The spatial Fourier modes of vorticity in turbulent jet and grid flows are analysed by means of an acoustic scattering technique. The Taylor Reynolds number ranges from 100 to 400. The dynamical properties of vorticity are investigated by computing the temporal correlations of the scattered signals. The range of probed wavenumbers spans the end of the inertial range down to the beginning of the dissipative range of the flow. The complex vorticity signal is dominated by the sweeping effects due to the advection of the small scales by the larger ones. The magnitude of the vorticity signal (enstrophy) exhibits two characteristic times : a short one related to the large-scale velocity gradients and a long time close to the integral time scale. This two times behavior is a manifestation of the temporal intermittency phenomenon. The evolution of the long time correlation level, with respect to the turbulent scales, is a consequence of spatial intermittency effects related to the lacunarity enhancement of the dissipative length scales.
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Nicolas Mazellier. Dynamique spatio-temporelle du champ de vorticité en turbulence : mesures par corrélation acoustique dynamique.. Energie électrique. Université Joseph-Fourier - Grenoble I, 2005. Français. ⟨tel-00011427⟩

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