OSCILLATORY MIGRATING MAGNETIC FIELDS IN HELICAL TURBULENCE IN SPHERICAL DOMAINS
2010 (English)In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 719, no 1, L1-L4 p.Article in journal (Refereed) Published
We present direct numerical simulations of the equations of compressible magnetohydrodynamics in a wedge-shaped spherical shell, without shear, but with random helical forcing which has negative (positive) helicity in the northern (southern) hemisphere. We find a large-scalemagnetic field that is nearly uniform in the azimuthal direction and approximately antisymmetric about the equator. Furthermore, the large-scale field in each hemisphere oscillates on nearly dynamical timescales with reversals of polarity and equatorward migration. Corresponding mean-field models also show similar migratory oscillations with a frequency that is nearly independent of the magnetic Reynolds number. This mechanism may be relevant for understanding equatorward migration seen in the solar dynamo.
Place, publisher, year, edition, pages
2010. Vol. 719, no 1, L1-L4 p.
IdentifiersURN: urn:nbn:se:su:diva-50197DOI: 10.1088/2041-8205/719/1/L1ISI: 000280853500001OAI: oai:DiVA.org:su-50197DiVA: diva2:380723
authorCount :42010-12-222010-12-212016-07-01Bibliographically approved