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The Elbert range of magnetostrophic convection. I. Linear theory

In magnetostrophic rotating magnetoconvection, a fluid layer heated from below and cooled from above is equidominantly influenced by the Lorentz and the Coriolis forces. Strong rotation and magnetism each act separately to suppress thermal convective instability. However, when they act in concert an...

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Autores principales: Horn, Susanne, Aurnou, Jonathan M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9364770/
https://www.ncbi.nlm.nih.gov/pubmed/35966215
http://dx.doi.org/10.1098/rspa.2022.0313
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author Horn, Susanne
Aurnou, Jonathan M.
author_facet Horn, Susanne
Aurnou, Jonathan M.
author_sort Horn, Susanne
collection PubMed
description In magnetostrophic rotating magnetoconvection, a fluid layer heated from below and cooled from above is equidominantly influenced by the Lorentz and the Coriolis forces. Strong rotation and magnetism each act separately to suppress thermal convective instability. However, when they act in concert and are near in strength, convective onset occurs at less extreme Rayleigh numbers ([Formula: see text] , thermal forcing) in the form of a stationary, large-scale, inertia-less, inviscid magnetostrophic mode. Estimates suggest that planetary interiors are in magnetostrophic balance, fostering the idea that magnetostrophic flow optimizes dynamo generation. However, it is unclear if such a mono-modal theory is realistic in turbulent geophysical settings. Donna Elbert first discovered that there is a range of Ekman ([Formula: see text] , rotation) and Chandrasekhar ([Formula: see text] , magnetism) numbers, in which stationary large-scale magnetostrophic and small-scale geostrophic modes coexist. We extend her work by differentiating five regimes of linear stationary rotating magnetoconvection and by deriving asymptotic solutions for the critical wavenumbers and Rayleigh numbers. Coexistence is permitted if [Formula: see text] and [Formula: see text]. The most geophysically relevant regime, the Elbert range, is bounded by the Elsasser numbers [Formula: see text]. Laboratory and Earth’s core predictions both exhibit stationary, oscillatory, and wall-attached multi-modality within the Elbert range.
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spelling pubmed-93647702022-08-11 The Elbert range of magnetostrophic convection. I. Linear theory Horn, Susanne Aurnou, Jonathan M. Proc Math Phys Eng Sci Research Articles In magnetostrophic rotating magnetoconvection, a fluid layer heated from below and cooled from above is equidominantly influenced by the Lorentz and the Coriolis forces. Strong rotation and magnetism each act separately to suppress thermal convective instability. However, when they act in concert and are near in strength, convective onset occurs at less extreme Rayleigh numbers ([Formula: see text] , thermal forcing) in the form of a stationary, large-scale, inertia-less, inviscid magnetostrophic mode. Estimates suggest that planetary interiors are in magnetostrophic balance, fostering the idea that magnetostrophic flow optimizes dynamo generation. However, it is unclear if such a mono-modal theory is realistic in turbulent geophysical settings. Donna Elbert first discovered that there is a range of Ekman ([Formula: see text] , rotation) and Chandrasekhar ([Formula: see text] , magnetism) numbers, in which stationary large-scale magnetostrophic and small-scale geostrophic modes coexist. We extend her work by differentiating five regimes of linear stationary rotating magnetoconvection and by deriving asymptotic solutions for the critical wavenumbers and Rayleigh numbers. Coexistence is permitted if [Formula: see text] and [Formula: see text]. The most geophysically relevant regime, the Elbert range, is bounded by the Elsasser numbers [Formula: see text]. Laboratory and Earth’s core predictions both exhibit stationary, oscillatory, and wall-attached multi-modality within the Elbert range. The Royal Society 2022-08 2022-08-10 /pmc/articles/PMC9364770/ /pubmed/35966215 http://dx.doi.org/10.1098/rspa.2022.0313 Text en © 2022 The Authors. https://creativecommons.org/licenses/by/4.0/Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, provided the original author and source are credited.
spellingShingle Research Articles
Horn, Susanne
Aurnou, Jonathan M.
The Elbert range of magnetostrophic convection. I. Linear theory
title The Elbert range of magnetostrophic convection. I. Linear theory
title_full The Elbert range of magnetostrophic convection. I. Linear theory
title_fullStr The Elbert range of magnetostrophic convection. I. Linear theory
title_full_unstemmed The Elbert range of magnetostrophic convection. I. Linear theory
title_short The Elbert range of magnetostrophic convection. I. Linear theory
title_sort elbert range of magnetostrophic convection. i. linear theory
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9364770/
https://www.ncbi.nlm.nih.gov/pubmed/35966215
http://dx.doi.org/10.1098/rspa.2022.0313
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