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Accueil > Actualités > Séminaires > Séminaires 2010

Mardi 7 décembre 2010 à 11:00 - salle A103 LEGI

Pablo Mininni (Departamento de Fisica, FCEN, Buenos Aires, ARGENTINA & National Center for Atmospheric Research, Boulder, USA)

Titre/Title :
Large-scale behavior of rotating turbulent flows

Contact :
Mickael Bourgoin (Equipe EDT)

Résumé/Abstract :
After a brief introduction to the effect of helicity in forced rotating flows, in this talk we discuss the decay of rotating flows in the presence and absence of net helicity. We present numerical simulations to analyze the cases of moderate Rossby number and large Reynolds number, focusing on the behavior of the energy spectrum at large scales, and studying its effect on the time evolution of the energy and integral scales for different initial conditions. The decay laws observed in the simulations point to a decoupling of the modes perpendicular to the rotation axis from the remaining three-dimensional (3D) modes. The slow modes show a behavior similar to that found in two-dimensional (2D) turbulence, whereas the 3D modes decay as isotropic turbulence. These results can be explained with phenomenological arguments that separate the decay of 2D from 3D modes, and that take into account the role of helicity and rotation in slowing down the energy decay. To this end, new integral conserved quantities that depend on the large-scale anisotropic spectrum have to be identified.