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Titel |
Mixed layer in a stably stratified fluid |
VerfasserIn |
F. Califano, A. Mangeney |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1023-5809
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Digitales Dokument |
URL |
Erschienen |
In: Nonlinear Processes in Geophysics ; 1, no. 4 ; Nr. 1, no. 4, S.199-208 |
Datensatznummer |
250000215
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Publikation (Nr.) |
copernicus.org/npg-1-199-1994.pdf |
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Zusammenfassung |
We present a numerical study of the generation and evolution of
a mixed layer in a stably stratified layer of Boussinesq fluid. We use an external forcing
in the equation of motion to model the experimental situation where the mechanical energy
input is due to an oscillating grid.
The results of 2D and 3D numerical simulations indicate that the basic mechanism for the
entrainment is the advection of the temperature field. This advection tends to produce
horizontally thin regions of small temperature vertical gradients (jets) where the
hydrodynamics forces are nearly zero. At the bottom of these structures, the buoyancy
brakes the vertical motions. The jets are also characterized by the presence of very short
horizontal scales where the thermal diffusion time turn out to be comparable with the
dynamics time. As a result, the temperature field is well mixed in a few dynamics times.
This process stops when the mechanical energy injected becomes comparable with the energy
dissipated by viscosity. |
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