Hostname: page-component-745bb68f8f-mzp66 Total loading time: 0 Render date: 2025-01-09T21:45:08.330Z Has data issue: false hasContentIssue false
  • English
  • Français

Double-averaging analysis and local flow characterization of near-bed turbulence in gravel-bed channel flows

Published online by Cambridge University Press:  10 January 2009

EMMANUEL MIGNOT ,
E. BARTHELEMY  and
D. HURTHER
EMMANUEL MIGNOT*
Affiliation:
Laboratoire des Ecoulements Géophysiques et Industriels (LEGI), BP 53, 38041 Grenoble Cedex 9, France
E. BARTHELEMY
Affiliation:
Laboratoire des Ecoulements Géophysiques et Industriels (LEGI), BP 53, 38041 Grenoble Cedex 9, France
D. HURTHER
Affiliation:
Laboratoire des Ecoulements Géophysiques et Industriels (LEGI), BP 53, 38041 Grenoble Cedex 9, France
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

This investigation focuses on the characteristics of near-bed turbulence in fully rough gravel-bed open-channel flows. The analysis combines results obtained with the double-averaging methodology and local flow characterization, using velocity measurements provided by a high-resolution three-axis Acoustic Doppler Velocity Profiler (ADVP). As a result of the flow heterogeneity induced by the bed topography, the flow is not locally uniform in the near-bed region, and a double-averaging methodology is applied over a length scale much greater than the gravel size. In smooth- and rough-bed flow conditions, without macro-roughness bed elements, maximum turbulent kinetic energy (TKE) production occurs very close to z = 0, while in our case with fully rough flows with macro-roughness elements, maximum turbulence activity is found to occur at gravel crest levels zc (zc/h = 0.1). Turbulent diffusion also reaches a maximum at this elevation. The characteristics of the spatially averaged TKE budget are in good agreement with those obtained in flows over canopies. The hydrodynamic double-averaged properties have strong similarities with mixing layers and reattached mixing layers in flows over backward facing steps. Local time-averaged velocity profiles can be split into three typical classes, namely log, S-shaped and accelerated. It appears that the S-shaped class profiles, located in the wakes of the macro-roughness elements, exhibit an inflectional profile typical of mixing layers. They are of major importance in the double-averaged TKE budget, as they provide a local high contribution to the double-averaged TKE flux, TKE production and dissipation compared to the log class profiles. Consequently, double-averaged TKE production is roughly 75% greater than the dissipation rate at the point of maximal TKE production. Moreover the macro-roughness bed elements imply mixing-layer-type hydrodynamics that play a dominant role in the overall structure of mean near-bed turbulence of gravel-bed channel flows.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 618 , 10 January 2009 , pp. 279 - 303
Copyright
Copyright © Cambridge University Press 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Aberle, J. 2007 Measurements of armour layer roughness geometry function and porosity. Acta Geophys. 55 (1), 23–32.CrossRefGoogle Scholar
Antonia, R. A. & Krogstad, P.-A. 2001 Turbulence structure in boundary layers over different types of surface roughness. Fluid Dyn. Res. 28, 139–157.CrossRefGoogle Scholar
Balachandar, R. & Bhuiyan, F. 2007 Higher-order moments of velocity fluctuations in an open-channel flow with large bottom roughness. J. Hydraul. Engng 133 (1), 77–87.CrossRefGoogle Scholar
Bigillon, F., Nino, Y. & Garcia, M. H. 2006 Measurements of turbulence characteristics in an open-channel flow over a transitionally-rough bed using particle image velocimetry. Exp. Fluids 41 (6), 857–867.CrossRefGoogle Scholar
Blanckaert, K. & de Vriend, H. J. 2004 Secondary flow in sharp open-channel bends. J. Fluid Mech. 498, 353–380.CrossRefGoogle Scholar
Blanckaert, K. & de Vriend, H. J. 2005 Turbulence structure in sharp open-channel bends. J. Fluid Mech. 536, 27–48.CrossRefGoogle Scholar
Britter, R. E. & Hanna, S. R. 2003 Flow and dispersion in urban areas. Ann. Rev. Fluid Mech. 35, 469–496.CrossRefGoogle Scholar
Buffin-Belanger, T. & Roy, A. G. 1998 Effects of pebble cluster on the turbulent structure of a depth-limited flow in a gravel-bed river. Geomorphology 25, 249–267.CrossRefGoogle Scholar
Castro, I. T. 2007 Rough-wall boundary layers: mean flow universality. J. Fluid Mech. 585, 469–485.CrossRefGoogle Scholar
Chaudry, M. H. 1993 Open-Channel Flow. Prentice Hall.Google Scholar
Chow, V. T. 1959 Open Channel Hydraulics. McGraw-Hill.Google Scholar
Coceal, O., Dobre, A. & Belcher, S. E. 2007 a Spatial variability of flow statistics within regular building arrays. Boundary-Layer Meteorol. 125, 537–552.CrossRefGoogle Scholar
Coceal, O., Dobre, A. & Thomas, T. G. 2007 b Unsteady dynamics and organized structures from dns over an idealized building canopy. Int. J. Climatol. 27, 1943–1953.CrossRefGoogle Scholar
Coceal, O., Dobre, A., Thomas, T. G. & Belcher, S. E. 2007 c Structure of turbulent flow over regular arrays of cubical roughness. J. Fluid Mech. 589, 375–409.CrossRefGoogle Scholar
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.CrossRefGoogle Scholar
Coleman, S., Nikora, V., McLean, S., Clunie, T. & Melville, B. 2007 Subelement form-drag parameterization in rough-bed flows. J. Hydraul. Engng 133 (2), 121–129.CrossRefGoogle Scholar
De Langres, E. 2008 Effects of wind on plants. Ann. Rev. Fluid Mech. 40, 141–168.CrossRefGoogle Scholar
Finnigan, J. 2000 Turbulence in plant canopies. Ann. Rev. Fluid Mech. 32, 519–571.CrossRefGoogle Scholar
Franca, M. J. 2005 a A field study of turbulent flows in shallow gravel-bed rivers. PhD thesis no. 3393, Ecole Polytechnique Federale de Lausanne, Switzerland.Google Scholar
Franca, M. J. 2005 b Flow dynamics over a gravel riverbed. In Proc. of the XXXI IAHR Congress, Seoul, Korea.Google Scholar
Franca, M. J. & Czernuszenko, W. 2006 Equivalent velocity profile for turbulent flows over gravel riverbeds. In Proc. River Flow 2006, Lisbon, Portugal.Google Scholar
Franca, M. J. & Lemmin, U. 2006 Turbulence measurements in shallow flows in gravel-bed rivers. In Proceeding of the 7th ICHE, Philadelphia, USA.Google Scholar
Garbini, J. L., Forster, F. K. & Jorgensen, J. E. 1982 Measurement of fluid turbulence based on pulsed ultrasound techniques. Part 1. Analysis. J. Fluid Mech. 118, 445–470.CrossRefGoogle Scholar
Graf, W. H. & Altinakar, M. 1998 Fluvial Hydraulics: Flow and Transport Processes in Channels of Simple Geometry. John Wiley.Google Scholar
Hoover, T. M. & Ackerman, J. D. 2004 Near-bed hydrodynamic measurements above boulders in shallow torrential streams: Implications for stream biota. J. Environ. Engng. Sci. 3, 365–378.CrossRefGoogle Scholar
Hurther, D. & Lemmin, U. 2000 Shear stress statistics and wall similarity analysis in turbulent boundary layers using a high-resolution 3-d ADVP. J. Oceanic Engng 25 (4), 446–457.CrossRefGoogle Scholar
Hurther, D. & Lemmin, U. 2001 A correction method for turbulence measurements with a 3d acoustic doppler velocity profiler. J. Atmos. Oceanic Technol. 18 (3), 446–458.2.0.CO;2>CrossRefGoogle Scholar
Hurther, D. & Lemmin, U. 2003 Turbulent particle flux and momentum flux statistics in suspension flow. Water Resour. Res. 39 (5)1139, doi:10.1029/2001WR001113.CrossRefGoogle Scholar
Hurther, D. & Lemmin, U. 2008 Improved turbulence profiling with field adapted acoustic doppler velocimeters using a bi-frequency doppler noise suppression method. J. Atmos. Oceanic Technol. 25 (3), 452–463.CrossRefGoogle Scholar
Hurther, D., Lemmin, U. & Terray, E. A. 2007 Turbulent transport in the outer region of rough wall open-channel flows: the contribution of large coherent shear stress structures (lc3s). J. Fluid Mech. 574, 465–493.CrossRefGoogle Scholar
Le, H., Moin, P. & Kim, J. 1997 Direct numerical simulation of turbulent flow over a backward-facing step. J. Fluid Mech. 330, 349–374.CrossRefGoogle Scholar
Lopez, F. & Garcia, M. H. 1999 Wall similarity in turbulent open channel flow. J. Engng Mech. 125, 789–796.Google Scholar
Lopez, F. & Garcia, M. H. 2001 Mean flow and turbulence structure of open-channel flow through non-emergent vegetation. J. Hydraul. Engng 127 (5), 392–402.CrossRefGoogle Scholar
Manes, C., Pokrajac, D. & McEwan, I. 2007 Double-averaged open-channel flows with small relative submergence. J. Hydraul. Engng 133 (8), 896–904.CrossRefGoogle Scholar
Mignot, E., Barthélemy, E. & Hurther, D. 2008 Turbulent kinetic energy budget in a gravel-bed channel flow. Acta Geophys. 56 (3), 601–613.CrossRefGoogle Scholar
Millikan, C. B. 1938 A critical discussion of turbulent flows in channels and circular pipes. In Proc. of 5th Intl Conf. on Applied Mechanics, New York.Google Scholar
Nakagawa, H. & Nezu, I. 1977 Prediction of the contribution to reynolds stress from bursting events in open-channel flows. J. Fluid Mech. 80 (1), 99–128.CrossRefGoogle Scholar
Nakagawa, H., Nezu, I. & Ueda, H. 1975 Turbulence of open channel flow over smooth and rough beds. Proc. Jpn. Soc. Civ. Eng. 241, 155–168.CrossRefGoogle Scholar
Nelson, J. M., McLean, S. R. & Wolfe, S. R. 1993 Mean flow and turbulence fields over two-dimensional bed forms. Water Resour. Res. 29 (12), 3935–3953.CrossRefGoogle Scholar
Nepf, H. & Ghisalberti, M. 2008 Flow and transport in channels with submerged vegetation. Acta Geophys. 56, 753–777.CrossRefGoogle Scholar
Nezu, I. 1993 Open-channel flow turbulence and its research prospect in the 21st century. J. Hydraul. Engng. 131 (4), 229–246.CrossRefGoogle Scholar
Nezu, I. & Nakagawa, H. 1993 Turbulence in open channel flows. IAHR Monograph, Balkema, Rotterdam, The Netherlands.Google Scholar
Nikora, V., Goring, D. & Biggs, B. 1998 On gravel-bed roughness characterization. Water Resour. Res. 34 (3), 517–527.CrossRefGoogle Scholar
Nikora, V., Goring, D., McEwan, I. & Griffiths, G. 2001 Spatially averaged open-channel flow over rough bed. J. Hydraul. Engng 127 (2), 123–133.CrossRefGoogle Scholar
Nikora, V., Koll, K., McEwan, I., McLean, S. & Dittrich, I. A. 2004 Velocity distribution in the roughness layer of rough-bed flows. J. Hydraulic Engng 130 (10), 1036–1042.CrossRefGoogle 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 (8), 873–883.CrossRefGoogle Scholar
Pope, S. B. 2003 Turbulent Flows. Cambridge University Press.Google Scholar
Raupach, M. R., Antonia, R. A. & Rajagopalan, S. 1981 Conditional statistics of reynolds stress in rough wall and smooth wall turbulent boundary layers. J. Fluid Mech. 108, 363–382.CrossRefGoogle Scholar
Raupach, M. R., Antonia, R. A. & Rajagopalan, S. 1991 Rough-wall turbulent boundary layers. Appl. Mech. Rev. 44 (1), 1–25.CrossRefGoogle Scholar
Raupach, M. R., Finnigan, J. J. & Brunet, Y. 1996 Coherent eddies and turbulence in vegetation canopies: the mixing layer analogy. Boundary-Layer Meteorol. 78, 351–382.CrossRefGoogle Scholar
Raupach, M. R. & Shaw, R. H. 1982 Averaging procedures for flow within vegetation canopies. Boundary-Layer Meteorol. 22, 79–90.CrossRefGoogle Scholar
Serafin, R. & Lhermitte, R. 1984 Pulse-to-pulse coherent doppler sonar signal processing techniques. J. Atmos. Oceanic Technol. 1 (4), 293–308.Google Scholar
Shen, C. & Lemmin, U. 1997 Ultrasonic scattering in highly turbulent clear water flow. Ultrasonics 35, 57–64.CrossRefGoogle Scholar
Song, T., Graf, W. H. & Lemmin, U. 1994 Uniform flow in open channels with movable gravel bed. J. Hydraul. Res. 32 (6), 861–876.CrossRefGoogle Scholar
Wilson, N. R. & Shaw, R. H. 1977 A higher order closure model for canopy flow. J. Appl. Meteorol. 16, 1197–1205.2.0.CO;2>CrossRefGoogle Scholar