Towards local isotropy of higher-order statistics in the intermediate wake

Abstract : In this paper, we assess the local isotropy of higher-order statistics in the intermediate wake region. We focus on normalized odd moments of the transverse velocity derivatives, M2n+1(partial derivative u/partial derivative z) = (partial derivative u/partial derivative z)(2n+1) / (partial derivative u/partial derivative z)(2) (2n+1)/2 and N2n+1 (partial derivative u/partial derivative y) = (partial derivative u/partial derivative y)(2n+1) /(partial derivative u/partial derivative y)(2) (2n+1)/2 which should be zero if local isotropy is satisfied (n is a positive integer). It is found that the relation M2n+1(partial derivative u/partial derivative z) similar to R-lambda(-1) is supported reasonably well by hot- wire data up to the direction of the mean shear; its effect on M2n+1(partial derivative u/partial derivative z) (in the non- shear direction) is negligible. seventh order (n = 3) on the wake centreline, although it is also dependent on the initial conditions. The present relation N3(partial derivative u/partial derivative y) similar to R-1 is obtained more rigorously than that proposed by Lumley (Phys Fluids 10: 855-858, 1967) via dimensional arguments. The effect of the mean shear at locations away from the wake centreline on M2n+ 1(partial derivative u/partial derivative z) and N2n+ 1(partial derivative u/partial derivative y) is addressed and reveals that, although the non- dimensional shear parameter is much smaller in wakes than in a homogeneous shear flow, it has a significant effect on the evolution of N2n+1(partial derivative u/partial derivative y) in the
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Experiments in Fluids, Springer Verlag (Germany), 2016, 57 (7), pp.111. 〈10.1007/s00348-016-2198-5〉
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Contributeur : Alexandre Poux <>
Soumis le : jeudi 5 octobre 2017 - 15:36:41
Dernière modification le : vendredi 26 octobre 2018 - 10:47:22

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S. L. Tang, R. A. Antonia, L. Danaila, L. Djenidi, T. Zhou, et al.. Towards local isotropy of higher-order statistics in the intermediate wake. Experiments in Fluids, Springer Verlag (Germany), 2016, 57 (7), pp.111. 〈10.1007/s00348-016-2198-5〉. 〈hal-01611238〉

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