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ON THE DECAY OF SHEARLESS WALL BOUNDED TURBULENCE

Jean Pierre Bertoglio
Laboratoire de Mecanique des Fluides et d'Acoustique UMR 5509 Ecole Centrale de Lyon 36 Av. Guy de Collongue, 69130 Ecully, FRANCE

L. Shao
LFMA, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69131 Ecully Cedex, France

H. Touil
Laboratoire de Mecanique des Fluides et d'Acoustique Ecole Centrale de Lyon, France

要約

The decay of turbulence in a wall bounded domain without mean velocity is investigated. Direct and Large-Eddy Simulations, as well as the Eddy Damped Quasi-Normal Marko-vian closure are used. The effect of the finite geometry of the domain is accounted for by introducing a low wave-number cutoff in the energy spectrum of isotropic turbulence. It is found that, once the saturation of the turbulent energy-containing length scale has occurred, the r.m.s. vorticity is decaying following a power law with a -3/2 exponent, in agreement with the helium superfluid experiment of Skrbek and Stalp (2000). The turbulent kinetic energy decay exponent is found to be -2, also in agreement with Skrbek and Stalp. Using scalings deduced from a simple analysis, all data can be collapsed into single curves for both the fixed scale turbulent regime and the final viscous period of decay. A spectral model for inhomogeneous turbulence is finally applied to the decay of turbulence between two plates. It is shown that the results are in agreement with the helium experiment.