Imperial College London

ProfessorMichaelLeschziner

Faculty of EngineeringDepartment of Aeronautics

Professor
 
 
 
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Contact

 

+44 (0)20 7594 5061mike.leschziner Website

 
 
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Location

 

CAGB317ACity and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Ghebali:2017:10.1063/1.5003617,
author = {Ghebali, S and Chernyshenko, SI and Leschziner, M},
doi = {10.1063/1.5003617},
journal = {Physics of Fluids},
title = {Can large-scale oblique undulations on a solid wall reduce the turbulent drag?},
url = {http://dx.doi.org/10.1063/1.5003617},
volume = {29},
year = {2017}
}

RIS format (EndNote, RefMan)

TY  - JOUR
AB - Direct numerical simulations of fully developed turbulent channel flows with wavy walls are undertaken. The wavy walls, skewed with respect to the mean flow direction, are introduced as a means of emulating a Spatial Stokes Layer (SSL) induced by in-plane wall motion. The transverse shear strain above the wavy wall is shown to be similar to that of a SSL, thereby affecting the turbulent flow and leading to a reduction in the turbulent skin-friction drag. However, some important differences with respect to the SSL case are brought to light too. In particular, the phase variations of the turbulent properties are accentuated and, unlike in the SSL case, there is a region of increased turbulence production over a portion of the wall, above the leeward side of the wave, thus giving rise to a local increase in dissipation. The pressure- and friction-drag levels are carefully quantified for various flow configurations, exhibiting a combined maximum overall-drag reduction of about 0.6%. The friction-drag reduction is shown to behave approximately quadratically for small wave slopes and then linearly for higher slopes, whilst the pressure-drag penalty increases quadratically. The transverse shear-strain layer is shown to be approximately Reynolds-number independent when the wave geometry is scaled in wall units.
AU - Ghebali,S
AU - Chernyshenko,SI
AU - Leschziner,M
DO - 10.1063/1.5003617
PY - 2017///
SN - 1070-6631
TI - Can large-scale oblique undulations on a solid wall reduce the turbulent drag?
T2 - Physics of Fluids
UR - http://dx.doi.org/10.1063/1.5003617
UR - http://hdl.handle.net/10044/1/50804
VL - 29
ER -