Journal ArticleDOI
Near-wall turbulence
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The current state of knowledge about the structure of wall-bounded turbulent flows is reviewed, with emphasis on the layers near the wall in which shear is dominant, and particularly on the logarithmic layer as mentioned in this paper.Abstract:
The current state of knowledge about the structure of wall-bounded turbulent flows is reviewed, with emphasis on the layers near the wall in which shear is dominant, and particularly on the logarithmic layer. It is shown that the shear interacts with scales whose size is larger than about one third of their distance to the wall, but that smaller ones, and in particular the vorticity, decouple from the shear and become roughly isotropic away from the wall. In the buffer and viscous layers, the dominant structures carrying turbulent energy are the streamwise velocity streaks, and the vortices organize both the dissipation and the momentum transfer. Farther from the wall, the velocity remains organized in streaks, although much larger ones than in the buffer layer, but the vortices lose their role regarding the Reynolds stresses. That function is taken over by wall-attached turbulent eddies with sizes and lifetimes proportional to their heights. Two kinds of eddies have been studied in some detail: vortex clusters, and ejections and sweeps. Both can be classified into a detached background, and a geometrically self-similar wall-attached family. The latter is responsible for most of the momentum transfer, and is organized into composite structures that can be used as models for the attached-eddy hierarchy hypothesized by Townsend [“Equilibrium layers and wall turbulence,” J. Fluid Mech.11, 97–120 (1961)]. The detached component seems to be common to many turbulent flows, and is roughly isotropic. Using a variety of techniques, including direct tracking of the structures, it is shown that an important characteristic of wall-bounded turbulence is temporally intermittent bursting, which is present at all distances from the wall, and in other shear flows. Its properties and time scales are reviewed, and it is shown that bursting is an important part of the production of turbulent energy from the mean shear. It is also shown that a linearized model captures many of its characteristics.read more
Citations
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Journal ArticleDOI
Coherent structures in wall-bounded turbulence
TL;DR: In this article, the authors describe wall-bounded turbulence as a deterministic high-dimensional dynamical system of interacting coherent structures, defined as eddies with enough internal dynamics to behave relatively autonomously from any remaining incoherent part of the flow.
Journal ArticleDOI
Two-point statistics for turbulent boundary layers and channels at Reynolds numbers up to δ + ≈ 2000
TL;DR: In this article, three-dimensional spatial correlations are investigated in very long domains to educe the average structure of the velocity and pressure fluctuations in the zero-pressure-gradient turbulent boundary layer in the range Re θ = 2780-6680.
Book ChapterDOI
Coherent Structures in Wall-Bounded Turbulence
TL;DR: In this article, the authors reviewed the current knowledge about some particular kinds of coherent structures in the logarithmic and outer layers of wall-bounded turbulent flows and argued that a concerned effort is required to quantitatively identify which one (or ones) of the plausible available dynamical models is a better representation of the observed behaviour.
Journal ArticleDOI
Time-resolved evolution of coherent structures in turbulent channels: characterization of eddies and cascades
TL;DR: In this paper, a novel approach to the study of the kinematics and dynamics of turbulent flows is presented, which involves tracking in time coherent structures, and provides all of the information required to characterize eddies from birth to death.
Journal ArticleDOI
Statistical structure of self-sustaining attached eddies in turbulent channel flow
TL;DR: In this paper, a self-sustaining energy-containing motion at each of the spanwise length scales is found to be self-similar with respect to the given span-wise length.
References
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Book
A First Course in Turbulence
Henk Tennekes,John L. Lumley +1 more
TL;DR: In this paper, the authors present a reference record created on 2005-11-18, modified on 2016-08-08 and used for the analysis of turbulence and transport in the context of energie.
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Turbulence statistics in fully developed channel flow at low reynolds number
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TL;DR: In this paper, the authors present a method to find the optimal set of words for a given sentence in a sentence using the Bibliogr. Index Reference Record created on 2004-09-07, modified on 2016-08-08
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