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Coherent structures - Reality and mythLarge-scale coherent structures (CS) in turbulent shear flows are characterized, reviewing recent theoretical and experimental investigations. The use of computers as a research tool and the flow-visualization experimental technique are introduced, CS are defined, the history of their discovery is traced, and their main characteristics are listed. Topics discussed and illustrated include the initial condition of the free shear layer, triple and double decomposition, topological features of CS, detection and eduction of CS, phase alignment via cross correlation, induced versus natural structures, the bursting phenomenon, turbulent spot, streaks, bursting frequency, the axisymmetric mixing layer, vortex pairing in an axisymmetric jet, CS and jet noise, broadband noise amplification via pure-tone excitation, CS interaction in a plane-jet near field, the Taylor hypothesis applied to CS, negative production, and the validity of the Reynolds-number similarity hypothesis. It is found that the coherent Reynolds stress, vorticity, and production are not much greater than the time-averaged values for fully developed flows with significant incoherent turbulence, suggesting that the importance of CS may have been exaggerated in some recent studies.
Document ID
19840028497
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Hussain, A. K. M. F.
(Houston, University Houston, TX, United States)
Date Acquired
August 12, 2013
Publication Date
October 1, 1983
Publication Information
Publication: Physics of Fluids
Volume: 26
ISSN: 0031-9171
Subject Category
Fluid Mechanics And Heat Transfer
Accession Number
84A11284
Distribution Limits
Public
Copyright
Other

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