Onset of Inertial Magnetoconvection in Rotating Fluid Spheres

The onset of convection in the form of magneto-inertial waves in a rotating fluid sphere permeated by a constant axial electric current is studied in this paper. Thermo-inertial convection is a distinctive flow regime on the border between rotating thermal convection and wave propagation. It occurs...

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Main Authors: Radostin D. Simitev, Friedrich H. Busse
Format: Article
Language:English
Published: MDPI AG 2021-01-01
Series:Fluids
Subjects:
Online Access:https://www.mdpi.com/2311-5521/6/1/41
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author Radostin D. Simitev
Friedrich H. Busse
author_facet Radostin D. Simitev
Friedrich H. Busse
author_sort Radostin D. Simitev
collection DOAJ
description The onset of convection in the form of magneto-inertial waves in a rotating fluid sphere permeated by a constant axial electric current is studied in this paper. Thermo-inertial convection is a distinctive flow regime on the border between rotating thermal convection and wave propagation. It occurs in astrophysical and geophysical contexts where self-sustained or external magnetic fields are commonly present. To investigate the onset of motion, a perturbation method is used here with an inviscid balance in the leading order and a buoyancy force acting against weak viscous dissipation in the next order of approximation. Analytical evaluation of constituent integral quantities is enabled by applying a Green’s function method for the exact solution of the heat equation following our earlier non-magnetic analysis. Results for the case of thermally infinitely conducting boundaries and for the case of nearly thermally insulating boundaries are obtained. In both cases, explicit expressions for the dependence of the Rayleigh number on the azimuthal wavenumber are derived in the limit of high thermal diffusivity. It is found that an imposed azimuthal magnetic field exerts a stabilizing influence on the onset of inertial convection and as a consequence magneto-inertial convection with azimuthal wave number of unity is generally preferred.
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spelling doaj.art-a4869916faaf4369862e08289688ed972023-12-03T13:03:00ZengMDPI AGFluids2311-55212021-01-01614110.3390/fluids6010041Onset of Inertial Magnetoconvection in Rotating Fluid SpheresRadostin D. Simitev0Friedrich H. Busse1School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UKInstitute of Physics, University of Bayreuth, 95440 Bayreuth, GermanyThe onset of convection in the form of magneto-inertial waves in a rotating fluid sphere permeated by a constant axial electric current is studied in this paper. Thermo-inertial convection is a distinctive flow regime on the border between rotating thermal convection and wave propagation. It occurs in astrophysical and geophysical contexts where self-sustained or external magnetic fields are commonly present. To investigate the onset of motion, a perturbation method is used here with an inviscid balance in the leading order and a buoyancy force acting against weak viscous dissipation in the next order of approximation. Analytical evaluation of constituent integral quantities is enabled by applying a Green’s function method for the exact solution of the heat equation following our earlier non-magnetic analysis. Results for the case of thermally infinitely conducting boundaries and for the case of nearly thermally insulating boundaries are obtained. In both cases, explicit expressions for the dependence of the Rayleigh number on the azimuthal wavenumber are derived in the limit of high thermal diffusivity. It is found that an imposed azimuthal magnetic field exerts a stabilizing influence on the onset of inertial convection and as a consequence magneto-inertial convection with azimuthal wave number of unity is generally preferred.https://www.mdpi.com/2311-5521/6/1/41rotating thermal magnetoconvectionlinear onsetsphere
spellingShingle Radostin D. Simitev
Friedrich H. Busse
Onset of Inertial Magnetoconvection in Rotating Fluid Spheres
Fluids
rotating thermal magnetoconvection
linear onset
sphere
title Onset of Inertial Magnetoconvection in Rotating Fluid Spheres
title_full Onset of Inertial Magnetoconvection in Rotating Fluid Spheres
title_fullStr Onset of Inertial Magnetoconvection in Rotating Fluid Spheres
title_full_unstemmed Onset of Inertial Magnetoconvection in Rotating Fluid Spheres
title_short Onset of Inertial Magnetoconvection in Rotating Fluid Spheres
title_sort onset of inertial magnetoconvection in rotating fluid spheres
topic rotating thermal magnetoconvection
linear onset
sphere
url https://www.mdpi.com/2311-5521/6/1/41
work_keys_str_mv AT radostindsimitev onsetofinertialmagnetoconvectioninrotatingfluidspheres
AT friedrichhbusse onsetofinertialmagnetoconvectioninrotatingfluidspheres