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TIME AND SPACE DEVELOPMENT OF ANISOTROPY IN A SPANWISE ROTATING CHANNEL

Sedat Tardu
Laboratoire des Ecoulements Geophysiques et Industriels (LEGI) UMR 5519/Universite de Grenoble 38402 Saint mrtin d'heres Cedex France

Julien Barenzung
Laboratoire des Ecoulements Géophysiques et Industriels (LEGI) B.P. 53 X 38041 Grenoble, Cédex, France

Sinopsis

Development of anisotropy in a spanwise rotating channel is analyzed in time and space through direct numerical simulations. The aim is to understand how the anisotropy sets-up both in time and space in a supercritical flow, the role of rotation being rather generic in this particular context. Several techniques to quantify anisotropy are used such as the trajectories in time and space of the Lumley invariants, the dissipation tensor invariants and local anisotropy characterization in spectral domain. It is shown that large excursions within the Lumley triangle occur near the centerline, and the local perturbation hesitates for long time between a one component to a nearly isotropic state. The wall damps these excursions; the local turbulence structure changes only slightly near the wall and it remains basically axisymmetric.