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Mixing across a density interface produced by grid turbulence

Published online by Cambridge University Press:  19 April 2006

P. F. Linden
P. F. Linden
Affiliation:
Department of Applied Mathematics, University of Cambridge, Silver Street, Cambridge CB3 9EW
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Abstract

The mixing produced by dropping a horizontal grid through a sharp density interface is examined experimentally. The fraction of the available kinetic energy used to mix the fluid, the flux Richardson number Rf, is measured as a function of the overall Richardson number Ri0. It is found that Rf increases from zero as Ri0 does, reaches a maximum, and then decreases with further increase in Ri0. The final interface thickness is found to be a decreasing function of Ri0, and the equivalent vertical diffusion coefficient is calculated. Qualitative observations of the flow show that the final stages of the decay of motion in the interface are characterized by pancake-shaped modes with large horizontal and small vertical scales.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 100 , Issue 4 , 29 October 1980 , pp. 691 - 703
Copyright
© 1980 Cambridge University Press

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References

Batchelor, G. K. & Townsend, A. A. 1948 Decay of isotropic turbulence in the initial period. Proc. Roy. Soc. A 193, 539.Google Scholar
Dickey, T. D. & Mellor, G. L. 1980 Decaying turbulence in neutral and stratified fluids. J. Fluid Mech. 99, 13.Google Scholar
Hoerner, S. F. 1965 Fluid-Dynamic Drag. (Write c/o A.I.A.A. New York for author's address.)
Linden, P. F. 1979 Mixing in stratified fluids. Geophys. & Astrophys. Fluid Dyn. 13, 3.Google Scholar
Naudascher, E. & Farell, C. 1970 Grid turbulence. Proc. A.S.C.E., J. Engng. Mech. Div. 96, 121.Google Scholar
Ozmidov, R. V. 1965 On the turbulent exchange in a stably stratified ocean. Bull. Acad. Sci. U.S.S.R., Atmos. & Oceanic Phys. 1, 257.Google Scholar
Pearson, H. J. 1980 Some aspects of turbulence in a stably stratified fluid: vertical diffusion and the final period of decay. Ph.D. thesis University of Cambridge.
Phillips, O. M. 1972 Turbulence in a stably stratified fluid: it is stable? Deep-Sea Res. 19, 79.Google Scholar
Posmentier, E. S. 1977 The generation of salinity fine structure by vertical diffusion. J. Phys. Ocean 7, 298.Google Scholar
Townsend, A. A. 1954 The diffusion behind a line source in homogeneous turbulence. Proc. Roy. Soc. A, 224, 487.Google Scholar
Weinstock, J. 1978 Vertical turbulent diffusion in a stably stratified fluid. J. Atmos. Sci. 35, 1022.Google Scholar