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Article: A three-dimensional spherical nonlinear interface dynamo

TitleA three-dimensional spherical nonlinear interface dynamo
Authors
KeywordsSun: Magnetic Fields
Issue Date2003
PublisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205
Citation
Astrophysical Journal Letters, 2003, v. 596 n. 1 I, p. 663-679 How to Cite?
AbstractA fully three-dimensional, nonlinear, time-dependent spherical interface dynamo is investigated using a finite-element method based on the three-dimensional tetrahedralization of the spherical system. The spherical interface dynamo model consists of four zones: an electrically conducting and uniformly rotating core, a thin differentially rotating tachocline, a uniformly rotating turbulent convection envelope, and a nearly insulating exterior. The four regions are coupled magnetically through matching conditions at the interfaces. Without the effect of a tachocline, the conventional nonlinear a 2 dynamo is always stationary, axisymmetric, and equatorially antisymmetric even though numerical simulations are always fully three-dimensional and time dependent. When there is no tachocline, the azimuthal field is confined to the convection zone while the poloidal magnetic field penetrates into the radiative core. The effects of an interface dynamo with a tachocline having a purely axisymmetric toroidal velocity field are as follows: (1) the action of the steady tachocline always gives rise to an oscillatory dynamo with a period of about 2 magnetic diffusion units, or about 20 yr if the magnetic diffusivity in the convection zone is 10 8 m 2 s -1; (2) the interface dynamo solution is always axisymmetric, selects dipolar symmetry, and propagates equatorward (for the assumed form of α) although the simulation is fully three-dimensional; (3) the generated magnetic field mainly concentrates in the vicinity of the interface between the tachocline and the convection zone; and (4) the strength of the toroidal magnetic field is dramatically amplified by the effect of the tachocline. Extensions of Cowling's theorem and the toroidal flow theorem to multilayer spherical shell regions with radially discontinuous magnetic diffusivities are presented.
Persistent Identifierhttp://hdl.handle.net/10722/156116
ISSN
2015 Impact Factor: 5.487
2015 SCImago Journal Rankings: 3.369
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorZhang, Ken_US
dc.contributor.authorChan, KHen_US
dc.contributor.authorZou, Jen_US
dc.contributor.authorLiao, Xen_US
dc.contributor.authorSchubert, Gen_US
dc.date.accessioned2012-08-08T08:40:28Z-
dc.date.available2012-08-08T08:40:28Z-
dc.date.issued2003en_US
dc.identifier.citationAstrophysical Journal Letters, 2003, v. 596 n. 1 I, p. 663-679en_US
dc.identifier.issn2041-8205en_US
dc.identifier.urihttp://hdl.handle.net/10722/156116-
dc.description.abstractA fully three-dimensional, nonlinear, time-dependent spherical interface dynamo is investigated using a finite-element method based on the three-dimensional tetrahedralization of the spherical system. The spherical interface dynamo model consists of four zones: an electrically conducting and uniformly rotating core, a thin differentially rotating tachocline, a uniformly rotating turbulent convection envelope, and a nearly insulating exterior. The four regions are coupled magnetically through matching conditions at the interfaces. Without the effect of a tachocline, the conventional nonlinear a 2 dynamo is always stationary, axisymmetric, and equatorially antisymmetric even though numerical simulations are always fully three-dimensional and time dependent. When there is no tachocline, the azimuthal field is confined to the convection zone while the poloidal magnetic field penetrates into the radiative core. The effects of an interface dynamo with a tachocline having a purely axisymmetric toroidal velocity field are as follows: (1) the action of the steady tachocline always gives rise to an oscillatory dynamo with a period of about 2 magnetic diffusion units, or about 20 yr if the magnetic diffusivity in the convection zone is 10 8 m 2 s -1; (2) the interface dynamo solution is always axisymmetric, selects dipolar symmetry, and propagates equatorward (for the assumed form of α) although the simulation is fully three-dimensional; (3) the generated magnetic field mainly concentrates in the vicinity of the interface between the tachocline and the convection zone; and (4) the strength of the toroidal magnetic field is dramatically amplified by the effect of the tachocline. Extensions of Cowling's theorem and the toroidal flow theorem to multilayer spherical shell regions with radially discontinuous magnetic diffusivities are presented.en_US
dc.languageengen_US
dc.publisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205en_US
dc.relation.ispartofAstrophysical Journal Lettersen_US
dc.subjectSun: Magnetic Fieldsen_US
dc.titleA three-dimensional spherical nonlinear interface dynamoen_US
dc.typeArticleen_US
dc.identifier.emailChan, KH:mkhchan@hku.hken_US
dc.identifier.authorityChan, KH=rp00664en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1086/377600en_US
dc.identifier.scopuseid_2-s2.0-0142198921en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0142198921&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume596en_US
dc.identifier.issue1 Ien_US
dc.identifier.spage663en_US
dc.identifier.epage679en_US
dc.identifier.isiWOS:000185814300054-
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridZhang, K=7404451892en_US
dc.identifier.scopusauthoridChan, KH=7406033542en_US
dc.identifier.scopusauthoridZou, J=8389644300en_US
dc.identifier.scopusauthoridLiao, X=7202134147en_US
dc.identifier.scopusauthoridSchubert, G=7201568549en_US

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