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Roughness effects on the Reynolds stress budgets in near-wall turbulence

Published online by Cambridge University Press:  03 November 2014

Junlin Yuan  and
Ugo Piomelli
Junlin Yuan*
Affiliation:
Department of Mechanical and Materials Engineering, Queen’s University, Kingston, ON K7L 3N6, Canada
Ugo Piomelli
Affiliation:
Department of Mechanical and Materials Engineering, Queen’s University, Kingston, ON K7L 3N6, Canada
*
†Email address for correspondence: junlin.yuan@queensu.ca
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Abstract

The physics of the roughness sublayer are studied by direct numerical simulations (DNS) of an open-channel flow with sandgrain roughness. A double-averaging (DA) approach is used to separate the spatial variations of the time-averaged quantities and the turbulent fluctuations. The spatial inhomogeneity of velocity and Reynolds stresses results in an additional production term for the turbulent kinetic energy (TKE) – the ‘wake production’; it is the excess wake kinetic energy (WKE), generated from the work of mean flow against the form drag, that is not directly dissipated into heat, but instead converted into turbulence. The wake production promotes wall-normal turbulent fluctuations and increases the pressure work, which ultimately leads to more homogeneous turbulence in the roughness sublayer, and to the increase of Reynolds shear stress and the drag on the rough wall. In the fully rough regime, roughness directly affects the generation of the wall-normal fluctuations, while in the transitionally rough regime, the region affected by roughness is separated from the region of intense generation of these fluctuations. The budget of the WKE and the connection between the wake and the turbulence suggest strong interactions between the roughness sublayer and the outer layer that are insensitive to the variation of the outer-layer conditions. Furthermore, the present results may have implications for the relationship between the roughness geometry and the flow dynamics in the region directly affected by roughness.

JFM classification

Turbulent Flows: Turbulence simulation Turbulent Flows: Turbulent boundary layers Turbulent Flows: Turbulent Flows
Type
Rapids
Information
Journal of Fluid Mechanics , Volume 760 , 10 December 2014 , R1
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Copyright
© 2014 Cambridge University Press 

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References

Coceal, O., Thomas, T. G., Castro, I. P. & Belcher, S. E. 2006 Mean flow and turbulence statistics over groups of urban-like cubical obstacles. Boundary-Layer Meteorol. 121, 491–519.Google Scholar
Colebrook, C. F. 1939 Turbulent flow in pipes with particular reference to the transition region between smooth- and rough-pipe laws. J. Inst. Civil Engrs 11, 133–156.CrossRefGoogle Scholar
Dey, S. & Das, R. 2012 Gravel-bed hydrodynamics: double-averaging approach. J. Hydraul. Engng 138, 707–725.Google Scholar
Dwyer, M. J., Patton, E. G. & Shaw, R. H. 1997 Turbulent kinetic energy budgets from a large-eddy simulation of airflow above and within a forest canopy. Boundary-Layer Meteorol. 84, 23–42.CrossRefGoogle Scholar
Finnigan, J. 2000 Turbulence in plant canopies. Annu. Rev. Fluid Mech. 32, 519–571.Google Scholar
Hong, J., Katz, J. & Schultz, M. P. 2011 Near-wall turbulence statistics and flow structures over three-dimensional roughness in a turbulent channel flow. J. Fluid Mech. 667, 1–37.Google Scholar
Hoyas, S. & Jiménez, J. 2008 Reynolds number effects on the Reynolds-stress budgets in turbulent channels. Phys. Fluids 20, 101511.Google Scholar
Ikeda, T. & Durbin, P. A. 2007 Direct simulations of a rough-wall channel flow. J. Fluid Mech. 571, 235–263.CrossRefGoogle Scholar
Jiménez, J. 2004 Turbulent flows over rough walls. Annu. Rev. Fluid Mech. 36, 173–196.Google Scholar
Kanda, M., Moriwaki, R. & Kasamatsu, F. 2004 Large-eddy simulation of turbulent organized structures within and above explicitly resolved cube arrays. Boundary-Layer Meteorol. 112, 343–368.CrossRefGoogle Scholar
Keating, A., Piomelli, U., Bremhorst, K. & Nešić, S. 2004 Large-eddy simulation of heat transfer downstream of a backward-facing step. J. Turbul. 5, N20.Google Scholar
Lee, J. H., Sung, H. J. & Krogstad, P.-Å. 2011 Direct numerical simulation of the turbulent boundary layer over a cube-roughened wall. J. Fluid Mech. 669, 397–431.Google Scholar
Leonardi, S. S. & Castro, I. P. 2010 Channel flow over large cube roughness: a direct numerical simulation study. J. Fluid Mech. 651, 519–539.Google Scholar
López, F. & García, M. H. 2001 Mean flow and turbulence structure of open-channel flow through non-emergent vegetation. J. Hydraul. Engng 127, 392–402.Google Scholar
Manes, C., Pokrajac, D. & McEwan, I. 2007 Double-averaged open-channel flows with small relative submergence. J. Hydraul. Engng 133, 896–904.Google Scholar
Mignot, E., Bartheleemy, E. & Hurther, D. 2009 Double-averaging analysis and local flow characterization of near-bed turbulence in gravel-bed channel flows. J. Fluid Mech. 618, 279–303.CrossRefGoogle Scholar
Nikora, V., Goring, D., McEwan, I. & Griffiths, G. 2001 Spatially averaged open-channel flow over rough bed. J. Hydraul. Engng 127, 123–133.CrossRefGoogle Scholar
Nikora, V., Koll, K., McEwan, I., McLean, S. & Dittrich, A. 2004 Velocity distribution in the roughness layer of rough-bed flows. J. Hydraul. Engng 130, 1036–1042.Google Scholar
Nikora, V., McEwan, I., McLean, S., Coleman, S., Pokrajac, D. & Walters, R. 2007 Double-averaging concept for rough-bed open-channel and overland flows: theoretical background. J. Hydraul. Engng 133, 873–883.Google Scholar
Orlandi, P. & Leonardi, S. 2008 Direct numerical simulation of three-dimensional turbulent rough channels: parameterization and flow physics. J. Fluid Mech. 606, 399–415.CrossRefGoogle Scholar
Raupach, M. R., Antonia, R. A. & Rajagopalan, S. 1991 Rough-wall boundary layers. Appl. Mech. Rev. 44, 1–25.CrossRefGoogle Scholar
Raupach, M. R. & Shaw, R. H. 1982 Averaging procedures for flow within vegetation canopies. Boundary-Layer Meteorol. 22, 79–90.Google Scholar
Schultz, M. P. & Flack, K. A. 2013 Reynolds-number scaling of turbulent channel flow. Phys. Fluids 25, 025104 1–13.Google Scholar
Scotti, A. 2006 Direct numerical simulation of turbulent channel flows with boundary roughened with virtual sandpaper. Phys. Fluids 18, 031701 1–4.Google Scholar
Yuan, J. & Piomelli, U. 2014 Numerical simulations of sink-flow boundary layers over rough surfaces. Phys. Fluids 26, 015113.Google Scholar