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De la turbulence 3D en déclin à la turbulence anisotrope dominée par la rotation

Abstract : The transition between isotropic 3D turbulence and anisotropic quasi-2D turbulence in a rotating frame is experimentally investigated. Turbulence is generated by rapidly towing a grid in a rotating water tank, and the velocity field in a plane perpendicular to the rotation axis is measured by means of particle image velocimetry. We first describe the differents regimes that characterize the energy decay: a range of approximate self-similar decay is found for times smaller than the Ekman time scale, instead of an exponential decay is found at larger times. The experimental decay exponents are found in good agreement with the predicted values from a phenomenological model, in which both the effects of the rotation and the confinement are taken into account. Even at very weak rotation rates, rotation is shown to have a strong influence on the decay law, by making the vertical integral scale to quickly growth through the propagation of inertial waves. Then we present the influence of a background rotation on the energy transfers from scale to scale. The velocity derivative skewness decreases with the microscopic Rossby number, reflecting the inhibition of the energy transfers by the background rotation. Finally, we present new results about the asymmetry between cyclones and anticyclones which characterize rotating flows. During the decay, a growth of the asymmetry towards cyclonic vorticity is observed as a power law of time as long as the confinement is negligible.
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Contributor : Cyprien Morize Connect in order to contact the contributor
Submitted on : Friday, January 5, 2007 - 7:06:41 PM
Last modification on : Thursday, December 10, 2020 - 12:32:00 PM
Long-term archiving on: : Friday, September 21, 2012 - 9:55:17 AM


  • HAL Id : tel-00122942, version 1




Cyprien Morize. De la turbulence 3D en déclin à la turbulence anisotrope dominée par la rotation. Physique [physics]. Université Paris-Diderot - Paris VII, 2006. Français. ⟨tel-00122942⟩



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