Hierarchical, self-sustained energy cascade to small scales in wall-bounded shear turbulence

Document Type

Book

Publication Date

1-1-1997

Abstract

The flow in the vicinity of a wall is dominated by large scale structures identified with alternating low-speed and high-speed streamwise streaks. These streaks periodically oscillate, break-up into small scale structures and reform. Most of the turbulence production, maintenance and transport occurs during the break-up of the structures, referred to as 'bursting event' in the literature. In this paper, we recall how well-chosen, low dimensional dynamical models mimic such intermittent dynamics and enlighten the crucial role played by the coupling between the mean flow and the fluctuation. In addition, we show how the fluctuation of the flow, in the normal (strongly inhomogeneous) direction, exhibits a cascade of energy toward small scales similar to the Kolmogorov energy cascade in homogeneous turbulence. More specifically, the flow is organized into families of modes. Within each family, all modes can be deduced from one another by stretching (i.e. scaling) symmetry. The spectral energy follows a well-defined decay law as the length scales are decreased.

Identifier

0030718973 (Scopus)

Publication Title

Advances in Fluid Mechanics

ISSN

1353808X

First Page

273

Last Page

308

Volume

15

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