Hostname: page-component-745bb68f8f-kw2vx Total loading time: 0 Render date: 2025-01-09T21:52:19.788Z Has data issue: false hasContentIssue false
  • English
  • Français

Near-field flow structure of a confined wall jet on flat and concave rough walls

Published online by Cambridge University Press:  10 July 2008

I. ALBAYRAK ,
E. J. HOPFINGER  and
U. LEMMIN
I. ALBAYRAK
Affiliation:
Laboratory of Environmental Hydraulics (LHE), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, [email protected]; [email protected]
E. J. HOPFINGER*
Affiliation:
LEGI-CNRS/UJF, Grenoble Cedex, [email protected]
U. LEMMIN
Affiliation:
Laboratory of Environmental Hydraulics (LHE), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, [email protected]; [email protected]
*
†Author to whom correspondence should be addressed.
Get access Rights & Permissions [Opens in a new window]

Abstract

Experimental results are presented of the mean flow and turbulence characteristics in the near field of a plane wall jet issuing from a nozzle onto flat and concave walls consisting of fixed sand beds. This is a flow configuration of interest for sediment erosion, also referred to as scouring. The measurements were made with an acoustic profiler that gives access to the three components of the instantaneous velocities. For the flat-wall flow, it is shown that the outer-layer spatial growth rate and the maxima of the Reynolds stresses approach the values accepted for the far field of a wall jet at a downstream distance x/b0 ≈ 8. These maxima are only about half the values of a plane free jet. This reduction in Reynolds stresses is also observed in the shear-layer region, x/b0 < 6, where the Reynolds shear stress is about half the value of a free shear layer. At distances x/b0 > 11, the maximum Reynolds shear stress approaches the value of a plane free jet. This change in Reynolds stresses is related to the mean vertical velocity that is negative for x/b0 < 8 and positive further downstream. The evolution of the inner region of the wall jet is found to be in good agreement with a previous model that explicitly includes the roughness length.

On the concave wall, the mean flow and the Reynolds stresses are drastically changed by the adverse pressure gradient and especially by the development of Görtler vortices. On the downslope side of the scour hole, the flow is nearly separating with the wall shear stress tending to zero, whereas on the upslope side, the wall-friction coefficient is increased by a factor of about two by Görtler vortices. These vortices extend well into the outer layer and, just above the wall, cause a substantial increase in Reynolds shear stress.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 606 , 10 July 2008 , pp. 27 - 49
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

Abrahamsson, H., Johansson, B. & Löfdahl, L. 1994 A turbulent plane two dimensional wall jet in a quiescent surrounding. Eur. J. Mech. Fluids. 13, 533–556.Google Scholar
Albayrak, I. 2007 Secondary currents and coherent structures, their distribution across a cross section and their relation to surface boils in turbulent gravel-bed open-channel flow. 32nd IAHR Congress, Venice, Italy, vol. 2, p. 767.Google Scholar
Albayrak, I. & Lemmin, U. 2007 Dynamics of secondary currents and surface boils in turbulent open-channel flow revealed by surface particle image velocity measurements. 32nd IAHR Congress, Venice, Italy, vol. 2, p. 486.Google Scholar
Barlow, R. S. & Johnston, J. P. 1985 Roll-cell structure in a concave turbulent boundary layer. AIAA Paper 85–0297.CrossRefGoogle Scholar
Chatterjee, S. S., Ghosh, S. N. & Chatterjee, M. 1994 Local scour due to a submerged horizontal jet. J. Hydraul. Engng. ASCE 120, 973–992.CrossRefGoogle Scholar
Diurno, G. V., Balaras, E. & Piomelli, U. 2001 Wall-layer models for LES of separated flows. ERCOFTAC Bull. 48, 37–40.Google Scholar
Eaton, J. K. & Johnston, J. P. 1980 Turbulent flow re-attachment: an experimental study of the flow and structure behind a backward-facing step. Stanford University, Rep. MD-39.Google Scholar
Eriksson, J., Karlsson, R. I. & Persson, J. 1998 An experimental study of a two dimensional plane wall jet. Exp. Fluids 25, 50–60.CrossRefGoogle Scholar
Floryan, J. M. 1991 On Görtler instability of boundary layers. Prog. Aerospace Sci. 28, 235–271.CrossRefGoogle Scholar
Franca, M. & Lemmin, U. 2005 Eliminating velocity aliasing in acoustic Doppler velocity profiler data. Meas. Sci. Technol. 16, 1–10.Google Scholar
George, W. K., Abrahamsson, H., Eriksson, J., Löfdahl, L., Karlsson, R. I. & Wosnik, M. 2000 A similarity theory for the turbulent plane wall jet without external stream. J. Fluid Mech. 425, 367–411.CrossRefGoogle Scholar
Grass, A. J. 1971 Structural features of turbulent flow over smooth and rough boundaries. J. Fluid Mech. 50, 233–255.CrossRefGoogle Scholar
Hogg, A. J., Huppert, H. E. & Dade, W. B. 1997 Erosion by planar turbulent wall jets. J. Fluid Mech. 338, 317–340.CrossRefGoogle Scholar
Hopfinger, E. J., Kurniawan, A., Graf, W. H. & Lemmin, U. 2004 Sediment erosion by Görtler vortices: the scour-hole problem. J. Fluid Mech. 520, 327–342.CrossRefGoogle Scholar
Hurther, D. & Lemmin, U. 2000 A correction method for turbulence measurements with a 3D acoustic Doppler velocity profiler. J. Atmosph. Ocean. Technol. 18, 446–458.2.0.CO;2>CrossRefGoogle Scholar
Karlsson, R. I., Ericsson, J. & Persson, J. 1992 LDV measurements of a plane jet in a large enclosure. Internal Rep. Department of Hydromechanics, Royal Institute of Technology, Sweden.Google Scholar
Kobayashi, R. & Fujisawa, N. 1983 Turbulence measurements in wall jets along strongly concave surfaces. Acta Mech. 477, 39–52.CrossRefGoogle Scholar
Kravchenko, A. G., Choi, H. & Moin, P. 1993 On the relations of near-wall streamwise vortices to wall skin friction in turbulent boundary layers. Phys. Fluids A 5, 3307–3309.CrossRefGoogle Scholar
Launder, B. E. & Rodi, W. 1981 The turbulent wall jet. Prog. Aerospace Sci. 19, 81–128.CrossRefGoogle Scholar
Launder, B. E. & Rodi, W. 1983 The turbulent wall jet-measurements and modelling. Annu. Rev. Fluid Mech. 15, 429–459.CrossRefGoogle Scholar
Lhermitte, R. & Lemmin, U. 1994 Open-channel flow and turbulent measurement by high-resolution Doppler sonar. J. Atmos. Ocean. Technd. 11, 1295–1308.2.0.CO;2>CrossRefGoogle Scholar
Mason, P. J. & Arumugam, K. 1985 Free jet scour below dams and flip buckets. J. Hydraul. Engng. ASCE 111, 220–235.CrossRefGoogle Scholar
Mayle, R. E., Blair, M. F. & Kopper, F. C. 1979 Turbulent boundary layer heat transfer on curved surfaces. Trans. ASME J. Heat Transfer 92, 521–525.CrossRefGoogle Scholar
Nielsen, P. 1992 Coastal Bottom Boundary Layers and Sediment Transport. World Scientific.CrossRefGoogle Scholar
Nino, Y. & Garcia, M. H. 1996 Experiments on particle–turbulence interactions in the near-wall region of an open-channel flow: implications for sediment transport. J. Fluid Mech. 326, 285–319.CrossRefGoogle Scholar
Pope, S. B. 2000 Turbulent Flows. Cambridge University Press.CrossRefGoogle Scholar
Rajaratnam, N. 1967 Hydraulic jumps. In Advances in Hydroscience (ed. Chow, V. T.), pp. 197–280. Academic.Google Scholar
Rajaratnam, N. 1981, Erosion by plane turbulent jets. J. Hydraul. Res. 19, 339–358.CrossRefGoogle Scholar
Rolland, T. & Lemmin, U. 1997 A two-component acoustic velocity profiler for use in turbulent open-channel flow. J. Hydraul. Res. 35, 545–561.CrossRefGoogle Scholar
Shen, C., Song, T. & Lemmin, U. 1998 Skin friction measurement in variable temperature flow. Proc. IEEE Instrumentation and Measurement Technology Conf. Brussels. pp. 523–526.Google Scholar
Sumer, B. M., Cokgor, S. & Fredsoe, J. 2001 Suction removal of sediment from between armor blocks. J. Hydr. Eng. 4, 293–206.CrossRefGoogle Scholar
Tamburrino, A. & Gulliver, J. S. 1999 Large flow structures in a turbulent open channel. J. Hydraul. Res. 37, 363–380.CrossRefGoogle Scholar
Wygnanski, I., Katz, Y. & Horev, E. 1992 On the applicability of various scaling laws to the turbulent wall jet. J. Fluid Mech. 234, 669–690.CrossRefGoogle Scholar
Zhou, M. D., Heine, C. & Wygnanski, I. 1996 The effects of excitation on the coherent and random motion in a plane wall jet. J. Fluid Mech. 310 1–37.CrossRefGoogle Scholar