Geophysical stratified turbulence and mixing in the laboratory

Geophysical fluid flows that are stably-stratified in density, like most of the ocean, can be strongly turbulent at small scales as a result of shear instabilities. The resulting mixing controls the vertical transport of heat and tracers that are key to large-scale layering and circulation patterns,...

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Main Author: Lefauve, Adrien
Format: Article
Language:English
Published: Académie des sciences 2024-09-01
Series:Comptes Rendus. Physique
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Online Access:https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.196/
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author Lefauve, Adrien
author_facet Lefauve, Adrien
author_sort Lefauve, Adrien
collection DOAJ
description Geophysical fluid flows that are stably-stratified in density, like most of the ocean, can be strongly turbulent at small scales as a result of shear instabilities. The resulting mixing controls the vertical transport of heat and tracers that are key to large-scale layering and circulation patterns, including those crucial to Earth’s climate. However, the physics of sheared stratified turbulence remain poorly understood due to their extraordinary range of scales and spatio-temporal intermittency. This paper reviews a laboratory model, the stratified inclined duct (SID), which encapsulates these fundamental physics and complexity while permitting precise control and measurements, a sweet spot to stimulate fruitful research. We explain how this exchange flow down a modest slope sustains high levels of energy dissipation and mixing while remaining strongly-stratified, thereby accessing the relevant geophysical parameter regime. Emphasising the role of detailed measurements, we highlight key discoveries and unsolved questions around the transition to turbulence, intermittent dynamics and parameterisations of mixing. Dimensional design guidelines show how the optical measurements of the full three-dimensional flow field could be perfected to extrapolate laboratory results to the tantalisingly close regime of the most intense geophysical stratified turbulence.
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spelling doaj-art-593163d3463b4b6f838e22b3070007c52025-02-07T13:54:24ZengAcadémie des sciencesComptes Rendus. Physique1878-15352024-09-0112910.5802/crphys.19610.5802/crphys.196Geophysical stratified turbulence and mixing in the laboratoryLefauve, Adrien0Department of Applied Mathematics and Theoretical Physics, University of Cambridge, United KingdomGeophysical fluid flows that are stably-stratified in density, like most of the ocean, can be strongly turbulent at small scales as a result of shear instabilities. The resulting mixing controls the vertical transport of heat and tracers that are key to large-scale layering and circulation patterns, including those crucial to Earth’s climate. However, the physics of sheared stratified turbulence remain poorly understood due to their extraordinary range of scales and spatio-temporal intermittency. This paper reviews a laboratory model, the stratified inclined duct (SID), which encapsulates these fundamental physics and complexity while permitting precise control and measurements, a sweet spot to stimulate fruitful research. We explain how this exchange flow down a modest slope sustains high levels of energy dissipation and mixing while remaining strongly-stratified, thereby accessing the relevant geophysical parameter regime. Emphasising the role of detailed measurements, we highlight key discoveries and unsolved questions around the transition to turbulence, intermittent dynamics and parameterisations of mixing. Dimensional design guidelines show how the optical measurements of the full three-dimensional flow field could be perfected to extrapolate laboratory results to the tantalisingly close regime of the most intense geophysical stratified turbulence.https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.196/turbulencemixinggeophysicalshearinstabilityintermittencyoceanparameterisation
spellingShingle Lefauve, Adrien
Geophysical stratified turbulence and mixing in the laboratory
Comptes Rendus. Physique
turbulence
mixing
geophysical
shear
instability
intermittency
ocean
parameterisation
title Geophysical stratified turbulence and mixing in the laboratory
title_full Geophysical stratified turbulence and mixing in the laboratory
title_fullStr Geophysical stratified turbulence and mixing in the laboratory
title_full_unstemmed Geophysical stratified turbulence and mixing in the laboratory
title_short Geophysical stratified turbulence and mixing in the laboratory
title_sort geophysical stratified turbulence and mixing in the laboratory
topic turbulence
mixing
geophysical
shear
instability
intermittency
ocean
parameterisation
url https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.196/
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