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On the large-scale structures in two-dimensional, small-deficit, turbulent wakes

Published online by Cambridge University Press:  21 April 2006

I. Wygnanski ,
F. Champagne  and
B. Marasli
I. Wygnanski
Affiliation:
Aerospace and Mechanical Engineering Department, University of Arizona, Tucson, AZ 85721, USA.
F. Champagne
Affiliation:
Aerospace and Mechanical Engineering Department, University of Arizona, Tucson, AZ 85721, USA.
B. Marasli
Affiliation:
Aerospace and Mechanical Engineering Department, University of Arizona, Tucson, AZ 85721, USA.
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Abstract

A systematic study of two-dimensional, turbulent, small-deficit wakes was carried out to determine their structure and the universality of their self-preserving states. Various wake generators, including circular cylinders, a symmetrical airfoil, a flat plate, and an assortment of screens of varying solidity, were studied for a wide range of downstream distances. Most of the generators were tailored so that their drag coefficients, and therefore their momentum thicknesses, were identical, permitting comparison at identical Reynolds numbers and aspect ratios. The flat plate and airfoil had a small, trailing-edge flap which could be externally driven to introduce forced sinuous oscillations into the wake. The results indicate that the normalized characteristic velocity and length scales depend on the initial conditions, while the shape of the normalized mean velocity profile is independent of these conditions or the nature of the generator. The normalized distributions of the longitudinal turbulence intensity, however, are dependent on the initial conditions.

Linear inviscid stability theory, in which the divergence of the mean flow is taken into account, predicts quite well the amplification and the transverse distributions of amplitudes and phases of externally imposed sinuous waves on a fully developed turbulent wake generated by a flat plate. There is a strong indication that the large structures observed in the unforced wake are related to the two-dimensional instability modes and therefore can be modelled by linear stability theory. Furthermore, the interaction of the two possible modes of instability may be responsible for the vortex street-type pattern observed visually in the small-deficit, turbulent wake.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 168 , July 1986 , pp. 31 - 71
Copyright
© 1986 Cambridge University Press

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References

Bouthier M.1972 J. Méc. 11, 599.
Brown, G. L. & Roshko A.1974 J. Fluid Mech. 64, 775.
Champagne F. H.1978 J. Fluid Mech. 86, 67.
Champagne F. H., Pao, Y. H. & Wygnanski I. J.1976 J. Fluid Mech. 74, 209.
Cimbala J., Nagib, H. & Roshko A.1981 Bull. Am. Phys. Soc. Ser. 11, 2.
Crighton, D. G. & Gaster M.1976 J. Fluid Mech. 77, 297.
Freymuth P.1966 J. Fluid Mech. 25, 683.
Gaster M., Kit, E. & Wygnanski I.1985 J. Fluid Mech. 150, 23.
Grant H. L.1958 J. Fluid Mech. 4, 149.
Karman Th. v., 1912 Nachr. Ges. Wiss. Göttingen 547.
Ko D. R. S., Kubota, T. & Lees L.1970 J. Fluid Mech. 40, 315.
Marasli B.1983 Master's thesis, AME Dept., University of Arizona.
Mattingly, G. E. & Criminale W. O.1972 J. Fluid Mech. 51, 233.
Michalke A.1965 J. Fluid Mech. 23, 521.
Narasimha, R. & Prabhu A.1972 J. Fluid Mech. 54, 1.
Oster, D. & Wygnanski I.1982 J. Fluid Mech. 123, 91.
Sato, H. & Kuriki K.1961 J. Fluid Mech. 11, 321.
Sreenivasan K. R.1981 AIAA J. 19, 1365.
Sreenivasan, K. R. & Narasimha R.1982 Trans. ASME J. Fluids Engng 104, 167.
Strange P. J. R.1982 Ph.D. thesis, University of Leeds.
Symes, C. R. & Fink L. E.1977 In Structures and Mechanisms of Turbulence I, proceedings. p. 86, Berlin.
Townsend A. A.1947 Proc. R. Soc. Lond. A 190, 551.
Townsend A. A.1949 Austral. J. Sci. 2, 451.
Townsend A. A.1956 The Structure of Turbulent Shear Flow. Cambridge University Press.
Townsend A. A.1970 The Structure of Turbulent Shear Flow, 2nd edn. Cambridge University Press.
Uberoi, M. S. & Freymuth P.1969 Phys. Fluids 12, 1359.
Wygnanski I., Oster, D. & Fiedler H.1979 In Proc. 2nd Symp. on Turbulent Shear Flows. London.
Yamada H., Kawata Y., Osaka, H. & Kageyama Y.1980 Tech. Rep. Yamaguchi University, Japan, vol. 2, no. 4.
Zabuski, N. J. & Deem G. S.1971 J. Fluid Mech. 47, 353.