Journal ArticleDOI
Turbulent Solar Convection and Its Coupling with Rotation: The Effect of Prandtl Number and Thermal Boundary Conditions on the Resulting Differential Rotation
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In this article, the authors developed a new computer code that, by exploiting massively parallel architectures, enables them to study fully turbulent spherical shell convection, and three of these solutions have a constant energy flux upper boundary condition.Abstract:
The dynamics of the vigorous convection in the outer envelope of the Sun must determine the transport of energy, angular momentum, and magnetic fields and must therefore be responsible for the observed surface activity and the angular velocity profile inferred helioseismically from SOI-MDI p-mode frequency splittings. Many different theoretical treatments have been applied to the problem, ranging from simple physical models such as mixing-length theory to sophisticated numerical simulations. Although mixing-length models provide a good first approximation to the structure of the convection zone, recent progress has mainly come from numerical simulations. Computational constraints have until now limited simulations in full spheres to essentially laminar convection. The angular velocity profiles have shown constancy on cylinders, in striking contrast to the approximately constant angular velocity on radial lines inferred for the Sun. In an effort to further our understanding of the dynamics of the solar convection zone, we have developed a new computer code that, by exploiting massively parallel architectures, enables us to study fully turbulent spherical shell convection. Here we present five fully evolved solutions. Motivated by the fact that a constant entropy upper boundary condition produces a latitudinal modulation of the emergent energy flux (of about 10%, i.e., far larger than is observed for the Sun), three of these solutions have a constant energy flux upper boundary condition. This leads to a latitudinal modulation of the specific entropy that breaks the constancy of the angular velocity on cylinders, making it more nearly constant on radial lines at midlatitudes. The effect of lowering the Prandtl number is also considered—highly time-dependent, vortical convective motions are revealed, and the Reynolds stresses are altered, leading to a reduced differential rotation. The differential rotation in all of our simulations shows a balance between driving by Reynolds stresses and damping by viscosity. This contrasts with the situation in the Sun, where the effect of viscosity on the mean differential rotation is almost negligible.read more
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Journal ArticleDOI
Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
TL;DR: In this article, a series of three-dimensional numerical simulations of MHD convection within rotating spherical shells using anelastic spherical harmonic (ASH) code on massively parallel supercomputers is presented.
Journal ArticleDOI
The Internal Rotation of the Sun
TL;DR: In this paper, a detailed observational picture has been built up of the internal rotation of our nearest star, showing that the radiative interior is found to rotate roughly uniformly, unlike the predictions of stellar evolution models, which had been that the rotation rate would depend primarily on the distance from the rotation axis.
Journal ArticleDOI
Dynamic variations at the base of the solar convection zone
R. Howe,Jørgen Christensen-Dalsgaard,Frank Hill,Rudolf Komm,R. M. Larsen,Jesper Schou,Michael Thompson,Juri Toomre +7 more
TL;DR: Changes in the rotation of the sun near the base of its convective envelope are detected, including a prominent variation with a period of 1.3 years at low latitudes, which may generate the 22-year cycles of magnetic activity.
Journal ArticleDOI
Simulations of Dynamo Action in Fully Convective Stars
TL;DR: In this paper, the authors present three-dimensional nonlinear magnetohydrodynamic simulations of the interiors of fully convective M dwarfs using the Anelastic Spherical Harmonic code, with the spherical computational domain extending from 0.08 to 0.96 times the overall stellar radius.
Journal ArticleDOI
Large-Scale Dynamics of the Convection Zone and Tachocline
TL;DR: In this article, the authors review observational, theoretical, and computational investigations of global-scale dynamics in the solar interior and highlight what they have learned from them and how they may be improved.
References
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Journal ArticleDOI
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Journal ArticleDOI
Differential Rotation and Dynamics of the Solar Interior
Michael Thompson,Juri Toomre,E. Anderson,H. M. Antia,Gabrielle Berthomieu,D. Burtonclay,S. M. Chitre,Joergen Christensen-Dalsgaard,Thierry Corbard,Marc L. DeRosa,Christopher R. Genovese,Douglas Gough,Deborah A. Haber,J. W. Harvey,Frank Hill,R. Howe,Sylvain G. Korzennik,Alexander G. Kosovichev,John Leibacher,Frank P. Pijpers,Janine Provost,Edward J. Rhodes,Jesper Schou,Takashi Sekii,Philip B. Stark,P. R. Wilson +25 more
TL;DR: Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths.
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