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Published October 25, 2010 | Submitted + Published
Journal Article Open

Large-eddy simulation of large-scale structures in long channel flow


We investigate statistics of large-scale structures from large-eddy simulation (LES) of turbulent channel flow at friction Reynolds numbers Re_τ = 2K and 200K (where K denotes 1000). In order to capture the behaviour of large-scale structures properly, the channel length is chosen to be 96 times the channel half-height. In agreement with experiments, these large-scale structures are found to give rise to an apparent amplitude modulation of the underlying small-scale fluctuations. This effect is explained in terms of the phase relationship between the large- and small-scale activity. The shape of the dominant large-scale structure is investigated by conditional averages based on the large-scale velocity, determined using a filter width equal to the channel half-height. The conditioned field demonstrates coherence on a scale of several times the filter width, and the small-scale–large-scale relative phase difference increases away from the wall, passing through π/2 in the overlap region of the mean velocity before approaching π further from the wall. We also found that, near the wall, the convection velocity of the large scales departs slightly, but unequivocally, from the mean velocity.

Additional Information

© 2010 Cambridge University Press. Received 22 November 2009; revised 27 May 2010; accepted 27 May 2010; first published online 23 August 2010. The authors acknowledge the support of the NSF under grants CBET-0651754 (DC) and CAREER-0747672 (BJM). It is our pleasure to acknowledge Professor Dale Pullin's generous support for this investigation, and useful discussions with Dr Ati Sharma and Dr Michele Guala.

Attached Files

Published - Chung2010p12028J_Fluid_Mech.pdf

Submitted - 1001.2915.pdf


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