Evolution of non-linear α2-dynamos and Taylor's constraint

D. R. Fearn*, M. M. Rahman

*المؤلف المقابل لهذا العمل

نتاج البحث: المساهمة في مجلةArticleمراجعة النظراء

8 اقتباسات (Scopus)


A key non-linear mechanism in a strong-field geodynamo is that a finite amplitude magnetic field drives a flow through the Lorentz force in the momentum equation and this flow feeds back on the field-generation process in the magnetic induction equation, equilibrating the field. We make use of a simpler non-linear α2-dynamo to investigate this mechanism in a rapidly rotating fluid spherical shell. Neglecting inertia, we use a pseudospectral time-stepping procedure to solve the induction equation and the momentum equation with no-slip velocity boundary conditions for a finitely conducting inner core and an insulating mantle. We present calculations for Ekman numbers (E) in the range 2.5 × 10-3 to 5.0 × 10-5, for α = α0 cos θ sin π(r - ri) (which vanishes on both inner and outer boundaries). Solutions are steady except at lower E and higher values of α0. Then they are periodic with a reversing field and a characteristic rapid increase then equally rapid decrease in magnetic energy. We have investigated the mechanism for this and shown the influence of Taylor's constraint. We comment on the application of our findings to numerical hydrodynamic dynamos.

اللغة الأصليةEnglish
الصفحات (من إلى)385-406
عدد الصفحات22
دوريةGeophysical and Astrophysical Fluid Dynamics
مستوى الصوت98
رقم الإصدار5
المعرِّفات الرقمية للأشياء
حالة النشرPublished - أكتوبر 2004
منشور خارجيًانعم

ASJC Scopus subject areas

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  • ???subjectarea.asjc.2200.2211???
  • ???subjectarea.asjc.1900.1906???


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