Abstract
This chapter discusses the physics underlying mixing caused by turbulent flow in a stratified fluid. The ability of the oceans to absorb and redistribute heat from the atmosphere at low latitudes is a crucial aspect of the climate system and accurate quantitative estimates of the mixing rates are critical to the development of reliable climate models. However, mixing occurs at very small scales where molecular diffusion is active and these processes cannot be calculated explicitly in climate models. Thus it is necessary to represent these rates in terms of the larger scale fields and this requires an understanding of the links between these large and small scales. We focus here on laboratory experiments that attempt to make these links and, in particular, represent transport rates in terms of a mixing efficiency. We show that insights can be obtained in this way that point to reasonable representations of mixing in geophysical flows.
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Acknowledgements
I would like to thank the organisers of this summer school for inviting me to give the lectures on which these notes are based. I would also like to acknowledge the many discussions I have had on this subject with many colleagues especially Colm Caulfield, Stuart Dalziel, Graham Hughes, Jamie Partridge, and John Taylor. This work is supported by the UK EPSRC, through the Programme Grant EP/K034529/1 and by the Royal Society.
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Linden, P.F. (2018). Turbulence and Mixing in Flows Dominated by Buoyancy. In: Clercx, H., Van Heijst, G. (eds) Mixing and Dispersion in Flows Dominated by Rotation and Buoyancy. CISM International Centre for Mechanical Sciences, vol 580. Springer, Cham. https://doi.org/10.1007/978-3-319-66887-1_2
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DOI: https://doi.org/10.1007/978-3-319-66887-1_2
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