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Dynamique des structures cohérentes en turbulence magnétohydrodynamique

Abstract : We experimentally investigated the temporal dynamics and the different transitions associated to the generation of large scale coherent structures in two-dimensional turbulence (2D). For a given dissipation rate, the increase of energy injected into the system gives rise to the formation of a large scale circulation, with spatial structures and temporal dynamics, which differ from the small-scale turbulent background. We have quantified a transition over a turbulent background . Moreover, the large scale flow exhibits a spectral signature commonly called " 1/f noise". As the forcing increases, we observed the emergence of a spatial configuration of vorticity. This state is often called , by analogy to the Bose-Einstein condensate, condensed regime. Due to the symmetry of the forcing, the large-scale flow may rotate in both directions. We observed stochastic reversals of the direction of the large-scale flow. The properties of these reversals are compared with the models proposed to explain reversals of Earth's magnetic field.
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https://tel.archives-ouvertes.fr/tel-00990150
Contributor : Herault Johann Connect in order to contact the contributor
Submitted on : Tuesday, May 13, 2014 - 11:24:27 AM
Last modification on : Thursday, March 17, 2022 - 10:08:09 AM
Long-term archiving on: : Monday, April 10, 2017 - 9:47:45 PM

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  • HAL Id : tel-00990150, version 1

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Johann Herault. Dynamique des structures cohérentes en turbulence magnétohydrodynamique. Mécanique des fluides [physics.class-ph]. Université Paris-Diderot - Paris VII, 2013. Français. ⟨tel-00990150⟩

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