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:2019:10.1103/physrevfluids.1.064401,
author = {Hwang, Y},
doi = {10.1103/physrevfluids.1.064401},
journal = {Physical Review Fluids},
title = {Mesolayer of attached eddies in turbulent channel flow},
url = {http://dx.doi.org/10.1103/physrevfluids.1.064401},
volume = {1},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Recent experimental measurements have reported that the outer peak of the streamwisewavenumber spectra of the streamwise velocity depends on the Reynolds number. Starting fromthis puzzling observation, here it is proposed that the wall-parallel velocity components of eachof the energy-containing motions in the form of Towsnend’s attached eddies exhibit inner-scalingnature in the region close to the wall. Some compelling evidence on this proposition has been presentedwith a careful inspection of scaling of velocity spectra from DNS, a linear analysis with aneddy viscosity, and the recently computed statistical structure of the self-similar energy-containingmotions in the logarithmic region. This observation suggests that the viscous wall effect wouldnot be negligible at least below the peak wall-normal location of each of the energy-containingmotions in the logarithmic and outer regions, reminiscent of the concept of the ‘mesolayer’ previouslyobserved in the mean momentum balance. It is shown that this behavior emerges due to aminimal form of scale interaction, modeled by the eddy viscosity in the linear theory, and enablesone to explain the Reynolds-number-dependent behavior of the outer peak as well as the near-wallpenetration of the large-scale outer structures in a consistent manner. Incorporation of this viscouswall effect to Townsend’s attached eddies, which were originally built with an inviscid approximationat the wall, also reveals that the self-similarity of the wall-parallel velocity components of theenergy-containing motions would be theoretically broken in the region close to the wall.
AU  - Hwang,Y
DO  - 10.1103/physrevfluids.1.064401
PY  - 2019///
SN  - 2469-990X
TI  - Mesolayer of attached eddies in turbulent channel flow
T2  - Physical Review Fluids
UR  - http://dx.doi.org/10.1103/physrevfluids.1.064401
UR  - http://hdl.handle.net/10044/1/39619
VL  - 1
ER  -
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