Hostname: page-component-6bb9c88b65-fsdjw Total loading time: 0 Render date: 2025-07-26T09:10:06.908Z Has data issue: false hasContentIssue false
  • English
  • Français

On the coherent structure of the axisymmetric mixing layer: a flow-visualization study

Published online by Cambridge University Press:  20 April 2006

A. K. M. F. Hussain  and
A. R. Clark
A. K. M. F. Hussain
Affiliation:
Department of Mechanical Engineering, University of Houston, Texas 77004
A. R. Clark
Affiliation:
Department of Mechanical Engineering, University of Houston, Texas 77004
Get access Rights & Permissions [Opens in a new window]

Abstract

In an effort to resolve some controversies regarding the turbulent mixing-layer structure, the near field of a large (18 cm diameter) air jet has been investigated for the jet exit speed of 30 m s−1. The smoke-laden axisymmetric mixing layer has been illuminated by a thin sheet of laser light in an azimuthal plane passing through the jet axis. High-speed visualization films of the mixing layer in the region of its self-preservation (of which a few picture sequences depicting space-time evolutions of the structure of the layer are presented) reveal that most of the time the mixing layer is in a state of disorganization, consisting of relatively smaller scale, random and diffuse turbulent motions; only occasionally are organized distinct large-scale coherent structures formed. The survival distances of the large-scale structures are found to be comparable to their average sizes. The survival time of these structures is about one ‘turnover’ time, each being roughly about five times the local characteristic time scale of the mixing layer. It is seen that tearing is as dominant a mode of large-scale interaction as pairing is; large-scale structures are continually sheared and typically fragmented due to a segment on the high-speed side being torn and swept away from the slower-moving outer portion. Evolution of the large structures occur not primarily through complete pairing as widely believed but quite frequently through ‘fractional pairing’ between segments which have been torn from different upstream large-scale coherent structures or through ‘partial pairing’ when one structure captures only a part of another. The movies show that along with entrainment of non-vortical ambient fluid, radially outward ejection of vortical fluid into the ambient is an important aspect of jet mixing. From aligned displays of ciné film frame sequences, space-time trajectories of identifiable vortical fluid elements have been traced. The convection velocity variation across the shear layer and even the overall structure convection velocity measured from these trajectories agree with those determined from the wave-number-celerity spectra, obtained from double-Fourier transformation of longitudinal velocity space-time correlation measurements with hot-wires.

The visualization films do not bear out the two-street vortex ring model recently propounded by Lau. Based on our observations, we propose that tearing, ‘slippage’ and fractional and partial pairings are responsible for the observed radial variation of structure passage frequency, and the causes of the different coherent structures educed by Bruun on the high- and low-speed sides of the mixing layer and for Yule's failure in educing a coherent structure on the low-speed side of the layer.

Information

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 104 , March 1981 , pp. 263 - 294
Copyright
© 1981 Cambridge University Press

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.)

Article purchase

Temporarily unavailable

References

Antonia, R. A., Chambers, A. J & Hussain, A. K. M. F. 1980 Phys. Fluids 23, 871.
Batt, R. G. 1975 A.I.A.A. J. 13, 245.
Batt, R. G. 1978 J. Fluid Mech. 82, 53.
Bradshaw, P. 1966 J. Fluid Mech. 26, 225.
Bradshaw, P., Feriss, D. H. & Johnson, R. F. 1964 J. Fluid Mech. 19, 591.
Bradshaw, P. 1977 J. Fluid Mech. 80, 795.
Browand, F. K. & Laufer, J. 1975 Turb. in Liquids 4, 333. Univ. of Missouri-Rolla.
Brown, G. L. & Roshko, A. 1974 J. Fluid Mech. 64, 775.
Bruun, H. H. 1977 J. Fluid Mech. 84, 641.
Champagne, F. H., Pao, Y. H. & Wygnanski, I. 1976 J. Fluid Mech. 74, 209.
Chandrsuda, C., Mehta, R. D., Weir, A. D. & Bradshaw, P. 1978 J. Fluid Mech. 85, 693.
Chevray, R. & Tutu, N. K. 1978 J. Fluid Mech. 88, 133.
Clark, A. R. 1979 Ph.D. dissertation, University of Houston.
Clark, A. R. & Hussain, A. K. M. F. 1981 (To be submitted.)
Corcos, G. M. & Sherman, F. S. 1976 J. Fluid Mech. 73, 241.
Corino, E. R. & Brodkey, R. S. 1969 J. Fluid Mech. 37, 1.
Crow, S. C. & Champagne, F. H. 1971 J. Fluid Mech. 48, 547.
Davies, P. O. A. L. & Baxter, D. R. J. 1978 In Structure and Mechanisms of Turbulence I, Lecture Notes in Physics, vol. 75 (ed. H. Fielder), p. 125. Springer.
Foss, J. F. 1977 Symp. Turb. Shear Flows, Penn State Univ., pp. 11.33–11.42.
Husain, Z. D. & Hussain, A. K. M. F. 1979 A.I.A.A. J. 17, 48.
Hussain, A. K. M. F. & Husain, Z. D. 1980 A.I.A.A. J. 18, 1462.
Hussain, A. K. M. F., Kleis, S. J. & Sokolov, M. 1980 J. Fluid Mech. 98, 97.
Hussain, A. K. M. F. & Thompson, C. A. 1980 J. Fluid Mech. 100, 397.
Hussain, A. K. M. F. & Zaman, K. B. M. Q. 1975 In Proc. 3rd Interagency Symp. on Univ. Res. in Transportation Noise, Univ. of Utah, p. 314.
Hussain, A. K. M. F. & Zaman, K. B. M. Q. 1977 Structure and Mechanisms of Turbulence I, Lecture Notes in Physics, vol. 75 (ed. H. Fiedler), p. 31. Springer.
Hussain, A. K. M. F. & Zaman, K. B. M. Q. 1980 J. Fluid Mech. 101, 493.
Hussain, A. K. M. F. & Zedan, M. F. 1978 Phys. Fluids 21, 1100.
Kleis, S. J. & Hussain, A. K. M. F. 1981 (To be submitted.)
Kline, S. J., Reynolds, W. C., Schraub, F. A. & Runstadler, P. W. 1967 J. Fluid Mech. 30, 741.
Ko, N. W. M. & Davies, P. O. A. L. 1971 J. Fluid Mech. 50, 49.
Kotsovinos, N. E. 1976 J. Fluid Mech. 77, 305.
Kovasznay, L. S. G., Kibens, V. & Blackwelder, R. F. 1970 J. Fluid Mech. 41, 283.
Landahl, M. T. 1967 J. Fluid Mech. 29, 441.
Lau, J. C. 1978 The vortex-street structure of turbulent jets. Part 2. (Submitted to J. Fluid Mech.)Google Scholar
Lau, J. C. & Fisher, M. J. 1975 J. Fluid Mech. 67, 229.
Lau, J. C., Fisher, M. J. & Fuchs, H. V. 1972 J. Sound Vib. 22, 379.
Laufer, J. 1974 In Ommagio a Carlo Ferrari (ed. Levrotto & Bella), p. 451.
Liepmann, H. 1978 Experimental approaches in fluid mechanics. Invited lecture at the 8th U.S. National Cong. on Applied Mechanics, UCLA.Google Scholar
Mollo-Christensen, E. 1967 Trans. A.S.M.E. E, J. Appl. Mech. 89, 1.
Moore, C. J. 1977 J. Fluid Mech. 80, 321.
Oster, D., Dziomba, B., Fiedler, H. & Wygnanski, I. 1977 In Structure and Mechanisms of Turbulence I, Lecture Notes in Physics, vol. 75 (ed. H. Fiedler), p. 48. Springer.
Patel, R. P. 1973 A.I.A.A. J. 13, 245.
Petersen, R. A. 1978 J. Fluid Mech. 89, 469.
Phillips, O. M. 1967 J. Fluid Mech. 29, 131.
Pui, N. K. & Gartshore, I. S. 1978 J. Fluid Mech. 91, 111.
Rockwell, D. O. 1972 Trans. A.S.M.E. E, J. Appl. Mech. 39, 883.
Saffman, P. G. 1978 J. Fluid Mech. 84, 625.
Sokolov, M., Hussain, A. K. M. F., Kleis, S. J. & Husain, Z. D. 1980 J. Fluid Mech. 98, 65.
Townsend, A. A. 1956 The Structure of Turbulent Shear Flow. Cambridge University Press.
Widnall, S. 1975 Ann. Rev. Fluid Mech. 89, 413.
Willmarth, W. W. & Wooldridge, C. E. 1962 J. Fluid Mech. 14, 187.
Wills, J. A. B. 1964 J. Fluid Mech. 20, 417.
Wills, J. A. B. 1970 J. Fluid Mech. 45, 65.
Winant, C. D. & Browand, F. K. 1974 J. Fluid Mech. 63, 237.
Yule, A. J. 1978 J. Fluid Mech. 89, 413.
Zaman, K. B. M. Q. & Hussain, A. K. M. F. 1980 J. Fluid Mech. 101, 449.
Zilberman, M., Wygnanski, I. & Kaplan, R. E. 1977 Phys. Fluids Suppl. 20, 258.