Imperial College London
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ProfessorSergeiChernyshenko

Faculty of Engineering, Department of Aeronautics

Chair in Aerodynamics
 
 
 
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Contact

 

+44 (0)20 7594 5548s.chernyshenko Website

 
 
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Location

 

211aCity and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Jiao:2022:10.1017/jfm.2022.300,
author = {Jiao, Y and Chernyshenko, S and Hwang, Y},
doi = {10.1017/jfm.2022.300},
journal = {Journal of Fluid Mechanics},
title = {A driving mechanism of near-wall turbulence subject to adverse pressure gradient in a plane Couette flow},
url = {http://dx.doi.org/10.1017/jfm.2022.300},
volume = {941},
year = {2022}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The effect of adverse pressure gradient (APG) on near-wall turbulence is studied, with a particular attention to the turbulence production mechanism. A plane turbulent Couette flow is considered for several values of constant APG in the lower wall region. A direct numerical simulation (DNS) in a large computational domain shows that turbulence near the lower wall continues to exist even at sufficiently large APGs. On increasing the APG, the cross-streamwise turbulence intensities increase, and the near-wall streaks gradually disappear. A linear analysis using the optimal transient growth indicates that the APG inhibits the generation of near-wall streaks due to the significant reduction of the mean shear in the region near the lower wall. The turbulent fluctuation dynamics beyond the linear regime is studied with a DNS in a minimal flow unit. The near-wall self-sustaining process involving streaks is significantly weakened or destroyed as APG increases, while the turbulent fluctuations become more isotropic and localised. Using a conditional averaging analysis, a new mechanism of near-wall turbulence production under strong APG is uncovered. This mechanism is initiated by the wall-normal nonlinear transport of an outer wall-normal velocity fluctuation to the near-wall region. The transported wall-normal velocity fluctuation is subsequently amplified via the Orr mechanism, resulting in the non-zero turbulence production involving spatially localised vortical structures. This mechanism is also confirmed by DNS of the flow in a large computational domain, where strong correlation between the wall-normal nonlinear transport and turbulence production is observed.
AU  - Jiao,Y
AU  - Chernyshenko,S
AU  - Hwang,Y
DO  - 10.1017/jfm.2022.300
PY  - 2022///
SN  - 0022-1120
TI  - A driving mechanism of near-wall turbulence subject to adverse pressure gradient in a plane Couette flow
T2  - Journal of Fluid Mechanics
UR  - http://dx.doi.org/10.1017/jfm.2022.300
UR  - http://hdl.handle.net/10044/1/96686
VL  - 941
ER  -
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