Imperial College London
Alternate

Dr. Yongyun Hwang

Faculty of Engineering, Department of Aeronautics

Reader in Fluid Mechanics
 
 
 
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Contact

 

+44 (0)20 7594 5078y.hwang

 
 
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Location

 

337City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Hwang:2016:10.1017/jfm.2016.470,
author = {Hwang, Y and Willis, AP and Cossu, C},
doi = {10.1017/jfm.2016.470},
journal = {Journal of Fluid Mechanics},
title = {Invariant solutions of minimal large-scale structures in turbulent channel flow for Reτ up to 1000},
url = {http://dx.doi.org/10.1017/jfm.2016.470},
volume = {802},
year = {2016}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Understanding the origin of large-scale structures in high Reynolds number wall turbulencehas been a central issue over a number of years. Recently, Rawat et al. (J.Fluid Mech., 2015, 782, p515) have computed invariant solutions for the large-scalestructures in turbulent Couette flow at Reτ  128 using an over-damped LES with theSmagorinsky model to account for the effect of the surrounding small-scale motions.Here, we extend this approach to an order of magnitude higher Reynolds numbers inturbulent channel flow, towards the regime where the large-scale structures in the formof very-large-scale motions (long streaky motions) and large-scale motions (short vorticalstructures) energetically emerge. We demonstrate that a set of invariant solutions canbe computed from simulations of the self-sustaining large-scale structures in the minimalunit (domain of size Lx = 3.0h streamwise and Lz = 1.5h spanwise) with midplanereflection symmetry at least up to Reτ  1000. By approximating the surrounding smallscales with an artificially elevated Smagorinsky constant, a set of equilibrium states arefound, labelled upper- and lower-branch according to their associated drag. It is shownthat the upper-branch equilibrium state is a reasonable proxy for the spatial structureand the turbulent statistics of the self-sustaining large-scale structures.
AU  - Hwang,Y
AU  - Willis,AP
AU  - Cossu,C
DO  - 10.1017/jfm.2016.470
PY  - 2016///
SN  - 1469-7645
TI  - Invariant solutions of minimal large-scale structures in turbulent channel flow for Reτ up to 1000
T2  - Journal of Fluid Mechanics
UR  - http://dx.doi.org/10.1017/jfm.2016.470
UR  - http://hdl.handle.net/10044/1/34701
VL  - 802
ER  -
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