Hostname: page-component-7b7567c8c-tnzcf Total loading time: 0 Render date: 2026-11-15T02:00:34.173Z Has data issue: false hasContentIssue false
  • English
  • Français

Streamwise vortex structure in plane mixing layers

Published online by Cambridge University Press:  21 April 2006

L. P. Bernal and
A. Roshko
L. P. Bernal
Affiliation:
Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, CA 91125, USAPresent Address: Department of Aerospace Engineering, The University of Michigan, Ann Arbor, Michigan 481092140, USA.
A. Roshko
Affiliation:
Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, CA 91125, USA
Get accessRights & Permissions [Opens in a new window]

Abstract

The development of three-dimensional motions in a plane mixing layer was investigated experimentally. It is shown that superimposed on the primary, spanwise vortex structure there is a secondary, steamwise vortex structure. Three aspects of this secondary structure were studied. First, the spanwise vortex instability that generates the secondary structure was characterized by measurements of the critical Reynolds number and the spanwise wavelength at several flow conditions. While the critical Reynolds number was found to depend on the velocity ratio, density ratio and initial shear-layer-profile shape, the mean normalized wavelength is independent of these parameters. Secondly, flow visualization in water was used to obtain cross-sectional views of the secondary structure associated with the streamwise counter-rotating vortices. A model is proposed in which those vortices are part of a single vortex line winding back and forth between the high-speed side of a primary vortex and the low-speed side of the following one. Finally, the effect of the secondary structure on the spanwise concentration field was measured in a helium–nitrogen mixing layer. The spatial organization of the secondary structure produces a well-defined spanwise entrainment pattern in which fluid from each stream is preferentially entrained at different spanwise locations. These measurements show that the spanwise scale of the secondary structure increases with downstream distance.

Information

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 170 , September 1986, pp. 499 - 525
Copyright
© 1986 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

Bernal L. P.1981 The coherent structure of turbulent mixing layers. Ph.D. thesis, California Institute of Technology.
Bradshaw P.1966 The effect of initial conditions on the development of a free shear layer. J. Fluid Mech. 26, 225–236.Google Scholar
Breidenthal R. E.1978 A chemically reacting turbulent shear layer. Ph.D. thesis, California Institute of Technology.
Breidenthal R. E.1979 Chemically reacting, turbulent shear layer. AIAA J. 17, 310–311.Google Scholar
Breidenthal R. E.1981 Structure in turbulent mixing layers and wakes using a chemical reaction. J. Fluid Mech. 109, 1–24.Google Scholar
Browand, F. K. & Troutt T. R.1980 A note on spanwise structure in the two-dimensional mixing layer. J. Fluid Mech. 97, 771–781.Google Scholar
Brown G. L.1974 The entrainment and large structure in turbulent mixing layers. Proc. 5th Australasian Conference on Hydraulics and Fluid Mechanis, pp. 352–359.
Brown, G. L. & Rebollo M. R.1972 A small, fast-response probe to measure composition of a binary gas mixture. AIAA J. 10, 649–652.Google Scholar
Brown, G. L. & Roshko A.1971 The effect of density difference on the turbulent mixing layer. AGARD-CP-93, pp. 23–1, 23–11.Google Scholar
Brown, G. L. & Roshko A.1974 On density effects and large structure in turbulent mixing layers. J. Fluid Mech. 64, 775–816.Google Scholar
Chandrsuda C., Mehta R. D., Weir, A. D. & Bradshaw P.1978 Effect of free stream turbulence on large structure in turbulent mixing layers. J. Fluid Mech. 85, 693–794.Google Scholar
Dewey C. F.1976 Qualitative and quantitative flow field visualization utilizing laser-induced fluorescence. AGARD-CP-193, pp. 17–1, 17–7.
Dimotakis, P. E. & Brown G. L.1976 The mixing layer at high Reynolds number: large-structure dynamics and entrainment. J. Fluid Mech. 78, 535–560.Google Scholar
Dimotakis P. E., Miake-Lye, R. C. & Papantoniou D. A.1983 Structure and dynamics of round turbulent jets. Phys. Fluids. 26, 3285–3192.Google Scholar
Hernan, M. A. & Jimenez J.1982 Computer analysis of a high-speed film of the plane turbulent mixing layer. J. Fluid Mech. 119, 323–345.Google Scholar
Ho, C.-M. & Huang L. S.1982 Subarmonics and vortex merging in mixing layers. J. Fluid Mech. 119, 445–473.Google Scholar
Ho, C.-M. & Huterre P.1984 Perturbed free shear layers. Ann. Rev. Fluid Mech. 16, 365–424.Google Scholar
Hussain A. K. M. F.1983 Coherent structures and incoherent turbulence. IUTAM Symp. on Turbulence and Chaotic Phenomena in Fluids. Sept. 5–10. Kyoto, Japan.Google Scholar
Jimenez J.1983 A spanwise structure in the plane shear layer. J. Fluid Mech. 132, 319–336.Google Scholar
Katz, J. & O'Hern T. J.1983 Cavitation in large scale shear flows. ASME paper 83-FE-33.Google Scholar
Konrad J. H.1976 An experimental investigation of mixing in two-dimensional turbulent shear flows with applications to diffusion-limited chemical reactions. Ph.D. thesis. California Institute of Technology. Also Project SQUID tec. rep. CIT-8-PU.
Lasheras J. C., Cho, J. S. & Maxworthy T.1986 On the origin and evolution of streamwise vortical structures in a plane, free shear layer. J. Fluid Mech. (in press).Google Scholar
Lin, S. J. & Corcos G. M.1984 The mixing layer: deterministic models of a turbulent flow. Part 3. The effect of plane strain on the dynamics of the streamwise vortices. J. Fluid Mech. 141, 139–178.Google Scholar
Miksad R. W.1972 Experiments on the nonlinear stages of free-shear layer transition. J. Fluid Mech. 56, 645–719.Google Scholar
Moore, D. W. & Saffman P. G.1975 The density of organized vortices in a turbulent mixing layer. J. Fluid Mech. 64, 465–473.Google Scholar
Patnaik P. C., Sherman, F. S. & Corcos G. M.1976 A numerical simulation of Kelvin—Helm-holtz waves of finite amplitude. J. Fluid Mech. 73, 215–240.Google Scholar
Pierrehumbert, R. T. & Widnall S. E.1982 The two- and three-dimensional instabilities of a spatially periodic shear layer. J. Fluid Mech. 114, 59–82.Google Scholar
Roshko A.1976 Structure of turbulent shear flows; a new look. AIAA J. 14, 1349–1357.Google Scholar
Winant, C. D. & Browasnd F. K.1974 Vortex pairing: the mechanism of turbulent mixing layer growth at moderate Reynolds number. J. Fluid Mech. 63, 237–255.Google Scholar
Wygnanski I., Oster D., Fiedler, H. & Dziomba B.1979 On the perseverance of a quasi-two-dimensional eddy-structure in a turbulent mixing layer. J. Fluid Mech. 93, 325–335.Google Scholar