Hostname: page-component-745bb68f8f-d8cs5 Total loading time: 0 Render date: 2025-01-08T17:01:16.075Z Has data issue: false hasContentIssue false
  • English
  • Français

Measurements of turbulence in a zero-mean-shear mixed layer

Published online by Cambridge University Press:  19 April 2006

Trevor J. Mcdougall
Trevor J. Mcdougall
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge Present address: Research School of Earth Sciences, The Australian National University, P.O. Box 4, Canberra 2600, ACT.
Get access Rights & Permissions [Opens in a new window]

Abstract

This paper is concerned with laboratory measurements of turbulence in a mixed layer and through a density interface, in the absence of a mean flow. The present results confirm the conclusion of Hopfinger & Toly (1976) that the turbulence in a mixed layer is not significantly affected by the slow entrainment of fluid across the bounding density interface. In a homogeneous fluid the turbulence intensity is found to be surprisingly non-uniform, even two grid mesh distances away from the grid. Velocity measurements have also been taken through a density interface (at the entraining boundary of a mixed layer) and the turbulence here varies in a manner that bears some resemblance to the theory of Hunt & Graham (1978). These velocity measurements were taken with a laser-Doppler anemometer and they were made possible by a novel experimental technique which eliminates the refractive index variations which normally occur in a turbulent, density-stratified liquid flow.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 94 , Issue 3 , 16 October 1979 , pp. 409 - 431
Copyright
© 1979 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

Crapper, P. F. & Linden, P. F. 1974 The structure of turbulent density interfaces. J. Fluid Mech. 65, 45–63.Google Scholar
Dimotakis, P. E. 1976 Single particle laser Doppler measurements of turbulence. AGARD Symp. Non-intrusive Instrument. in Fluid Flow Res., Saint-Louis, France, paper 10.
Gill, A. E. & Turner, J. S. 1976 A comparison of seasonal thermocline models with observation. Deep-Sea Res. 23, 391–401.Google Scholar
Hoesel, W. & Rodi, W. 1977 New biasing elimination method for laser-Doppler velocimeter counter processing. Rev. Sci. Instrum. 48, 910–919.Google Scholar
Hopfinger, E. J. & Toly, J.-A. 1976 Spatially decaying turbulence and its relation to mixing across density interfaces. J. Fluid Mech. 78, 155–175.Google Scholar
Hunt, J. C. R. & Graham, J. M. R. 1978 Free-stream turbulence near plane boundaries. J. Fluid Mech. 84, 209–235.Google Scholar
Huppert, H. E. & Manins, P. C. 1973 Limiting conditions for salt-fingering at an interface. Deep-Sea Res. 20, 315–323.Google Scholar
Kato, H. & Phillips, O. M. 1969 On the penetration of a turbulent layer into a stratified fluid. J. Fluid Mech. 37, 643–655.Google Scholar
Kraus, E. B. & Turner, J. S. 1967 A one-dimensional model of the seasonal thermocline. II. The general theory and its consequences. Tellus 19, 98–106.Google Scholar
Long, R. R. 1975 The influence of shear on mixing across density interfaces. J. Fluid Mech. 70, 305–320.Google Scholar
Long, R. R. 1977 Some aspects of turbulence in geophysical systems. Adv. Appl. Mech. 17, 1–90.Google Scholar
Long, R. R. 1978 A theory of mixing in a stably stratified fluid. J. Fluid Mech. 84, 113–124.Google Scholar
McDougall, T. J. 1978 Some aspects of geophysical turbulence. Ph.D. thesis, University of Cambridge.
McDougall, T. J. 1979a On the elimination of refractive index variations in turbulent densitystratified liquid flows. J. Fluid Mech. 93, 83.Google Scholar
McDougall, T. J. 1979b Bias correction for individual realization laser-Doppler anemometer measurements. J. Phys. E. (in press).Google Scholar
McLaughlin, D. K. & Tiederman, W. G. 1973 Biasing correction for individual realization of laser anemometer measurements in turbulent flows. Phys. Fluids 16, 2082–2088.Google Scholar
Niiler, P. P. & Kraus, E. B. 1977 One-dimensional models. In Modelling and Prediction of the Upper Layers of the Ocean (ed. E. B. Kraus). Oxford: Pergamon Press.
Thomas, N. H. & Hancock, P. E. 1977 Grid turbulence near a moving wall. J. Fluid Mech. 82, 481–496.Google Scholar
Thompson, S. M. 1969 Turbulent interfaces generated by an oscillating grid in a stably stratified fluid. Ph.D. thesis, University of Cambridge.
Thompson, S. M. & Turner, J. S. 1975 Mixing across an interface due to turbulence generated by an oscillating grid. J. Fluid Mech. 67, 349–368.Google Scholar
Turner, J. S. 1968 The influence of molecular diffusivity on turbulent entrainment across a density interface. J. Fluid Mech. 23, 639–656.Google Scholar
Turner, J. S. 1973 Buoyancy Effects in Fluids. Cambridge University Press.
Turner, J. S. & Kraus, E. B. 1967 A one-dimensional model of the seasonal thermocline. I. A laboratory experiment and its interpretation. Tellus 19, 88–97.Google Scholar
Wolanski, E. J. & Brush, L. M. 1975 Turbulent entrainment across stable density step structures. Tellus 27, 259–268.Google Scholar