Spontaneous layering in stratified turbulent Taylor–Couette flow

Oglethorpe, R. L. F. and Caulfield, C. P. and Woods, Andrew W. (2013) Spontaneous layering in stratified turbulent Taylor–Couette flow. Journal of Fluid Mechanics, 721. R3. DOI 10.1017/jfm.2013.85

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Abstract

We conduct a series of laboratory experiments to study the mixing of an initially linear stratification in turbulent Taylor–Couette flow. We vary the inner radius, R1{R}_{1} , and rotation rate, Ω\Omega , relative to the fixed outer cylinder, of radius R2{R}_{2} , as well as the initial buoyancy frequency N0=(−g/ρ)∂ρ/∂z−−−−−−−−−−−√{N}_{0} = \sqrt{(- g/ \rho )\partial \rho / \partial z} . We find that a linear stratification spontaneously splits into a series of layers and interfaces. The characteristic height of these layers is proportional to UH/N0{U}_{H} / {N}_{0} , where UH=R1ΔR−−−−−√Ω{U}_{H} = \sqrt{{R}_{1} { \mathrm{\Delta} }_{R} } \Omega is a horizontal velocity scale, with ΔR=R2−R1{ \mathrm{\Delta} }_{R} = {R}_{2} - {R}_{1} the gap width of the annulus. The buoyancy flux through these layers matches the equivalent flux through a two-layer stratification, independently of the height or number of layers. For a strongly stratified flow, the flux tends to an asymptotic constant value, even when multiple layers are present, consistent with Woods et al. (J. Fluid Mech., vol. 663, 2010, pp. 347–357). For smaller stratification the flux increases, reaching a maximum just before the layers disappear due to overturning of the interfaces.

Item Type: Article
Uncontrolled Keywords: 2013AREP; IA66;
Subjects: 99 - Other
Divisions: 99 - Other
Journal or Publication Title: Journal of Fluid Mechanics
Volume: 721
Page Range: R3
Identification Number: 10.1017/jfm.2013.85
Depositing User: Sarah Humbert
Date Deposited: 12 Jul 2013 16:45
Last Modified: 08 Aug 2013 12:15
URI: http://eprints.esc.cam.ac.uk/id/eprint/2833

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