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dc.contributor.authorChang, E.
dc.contributor.authorGaraud, P.
dc.date.accessioned2021-11-29T20:24:39Z
dc.date.available2021-11-29T20:24:39Z
dc.date.issued2021
dc.identifier.citationChang, E., & Garaud, P. (2021). Modelling coexisting GSF and shear instabilities in rotating stars. Monthly Notices of the Royal Astronomical Society.
dc.identifier.issn0035-8711
dc.identifier.doi10.1093/mnras/stab1927
dc.identifier.urihttp://hdl.handle.net/10150/662377
dc.description.abstractZahn's widely used model for turbulent mixing induced by rotational shear has recently been validated (with some caveats) in non-rotating shear flows. It is not clear, however, whether his model remains valid in the presence of rotation, even though this was its original purpose. Furthermore, new instabilities arise in rotating fluids, such as the Goldreich-Schubert-Fricke (GSF) instability. Which instability dominates when more than one can be excited, and how they influence each other, were open questions that this paper answers. To do so, we use direct numerical simulations of diffusive stratified shear flows in a rotating triply periodic Cartesian domain located at the equator of a star. We find that either the GSF instability or the shear instability tends to take over the other in controlling the system, suggesting that stellar evolution models only need to have a mixing prescription for each individual instability, together with a criterion to determine which one dominates. However, we also find that it is not always easy to predict which instability 'wins' for given input parameters, because the diffusive shear instability is subcritical, and only takes place if there is a finite-amplitude turbulence 'primer' to seed it. Interestingly, we find that the GSF instability can in some cases play the role of this primer, thereby providing a pathway to excite the subcritical shear instability. This can also drive relaxation oscillations, which may be observable. We conclude by proposing a new model for mixing in the equatorial regions of stellar radiative zones due to differential rotation. © 2021 The Author(s).
dc.language.isoen
dc.publisherOxford University Press
dc.rightsCopyright © 2021 The Author(s).
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectHydrodynamics
dc.subjectInstabilities
dc.subjectStars: Evolution
dc.subjectTurbulence
dc.titleModelling coexisting GSF and shear instabilities in rotating stars
dc.typeArticle
dc.typetext
dc.contributor.departmentGraduate Interdisciplinary Program in Applied Mathematics, University of Arizona
dc.identifier.journalMonthly Notices of the Royal Astronomical Society
dc.description.noteImmediate access
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.
dc.eprint.versionFinal published version
dc.source.journaltitleMonthly Notices of the Royal Astronomical Society
refterms.dateFOA2021-11-29T20:24:39Z


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