Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-17T19:44:15.251Z Has data issue: false hasContentIssue false
  • English
  • Français

Computer analysis of a high-speed film of the plane turbulent mixing layer

Published online by Cambridge University Press:  20 April 2006

Miguel A. Hernan  and
Javier Jimenez
Miguel A. Hernan
Affiliation:
School of Aeronautics, Universidad Politecnica de Madrid, Spain Present address: Department of Aeronautics, California Institute of Technology, Pasadena, U.S.A.
Javier Jimenez
Affiliation:
School of Aeronautics, Universidad Politecnica de Madrid, Spain Present address: Department of Applied Mathematics, California Institute of Technology, Pasadena, U.S.A.
Get access Rights & Permissions [Opens in a new window]

Abstract

To evaluate the usefulness of digital image analysis in extracting quantitative information from flow pictures we have studied a 16 mm ciné film of a turbulent mixing layer. A sequence of 373 frames is digitized and analysed to isolate and measure the concentration eddies that constitute the large structure and to follow their individual evolution in time. As a result, statistics are given on the life history of the eddies, the structure of the amalgamation process and the amount of entrainment, as measured by area change, due to amalgamation as compared to the total. It is found that most of the entrainment occurs during the normal life of eddies and not during pairing. Mixing intermittency is computed from the observed shape of the eddies and seen to compare well with previous measurements. The significance of these results in modelling the mixing layer is discussed briefly and some comments are given on the general usefulness of the techniques presented.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 119 , June 1982 , pp. 323 - 345
Copyright
© 1982 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.)

References

Brown, G. L. & Roshko, A. 1974 On density effects and large structure on turbulent mixing layers. J. Fluid Mech. 64, 775–816.Google Scholar
Chow, C. K. & Kaneko, T. 1972 Boundary detection of radiographic images by a threshold method. In Frontiers in Pattern Recognition (ed. S. Watanabe), pp. 61–82. Academic.
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
Fu, K. S. 1974 Syntactic Methods in Pattern Recognition. Academic.
Jimenez, J. 1980 On the visual growth of a turbulent mixing layer. J. Fluid Mech. 96, 447–460.Google Scholar
Jimenez, J., Martinez-Val, R. & Hernan, M. A. 1981 Shear layer models and computer analysis of data. In The Role of Coherent Structures in Modelling Turbulence and Mixing (ed. J. Jimenez). Lecture Notes in Physics, vol. 136, pp. 41–61. Springer.
Jimenez, J., Martinez-Val, R. & Rebollo, M. 1979a The spectrum of large scale structure in a mixing layer. In Proc. 2nd Symp. on Turbulent Shear Flows, London, pp. 8.7–8.11.
Jimenez, J., Martinez-Val, R. & Rebollo, M. 1979b On the origin and evolution of three dimensional effects in the mixing layer. Universidad Politecnica de Madrid Final Report, DA-ERO 79-G-079.
Konrad, J. H. 1976 An experimental investigation of mixing in two-dimensional turbulent shear flows with application to diffusion-limited chemical reactions. Ph.D. thesis, California Institute of Technology. Tech. Rep. CIT-8-PU.Google Scholar
Koochesfahani, M. M., Catherasoo, C. J., Dimotakis, P. E., Gharib, M. & Lang, D. B. 1979 Two-point LDV measurements in a plane mixing layer. A.I.A.A. J. 17, 1347–1351.Google Scholar
Moore, D. W. & Saffman, P. G. 1975 The density of organized vortices in a turbulent mixing layer. J. Fluid Mech. 69, 465–473.Google Scholar
Pavlidis, T. 1977 Structural Pattern Recognition. Springer.
Pratt, W. K. 1978 Digital Image Processing. Wiley.
Roshko, A. 1976 Structure of turbulent shear flows: a new look. A.I.A.A. Paper no. 76–78.Google Scholar
Roshko, A. 1980 The plane mixing layer, flow visualization results and three dimensional effects. In The Role of Coherent Structures in Modelling Turbulence and Mixing (ed. J. Jimenez). Lecture Notes in Physics, vol. 136, pp. 208–217. Springer.
Saffman, P. G. 1980 Vortex interactions and coherent structures in turbulence. In Proc. Symp. on Transition and Turbulence, Madison. Academic.
Townsend, A. A. 1956 The Structure of Turbulent Shear Flow, Cambridge University Press.
Winant, C. D. & Browand, F. K. 1974 Vortex pairing: the mechanism of turbulent mixing-layer growth at moderate Reynolds number. J. Fluid Mech. 63, 237–255.Google Scholar