Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Turbulent 3D MHD dynamo model in spherical shells: Regular oscillations
  of the dipolar field   We report the results of three-dimensional numerical simulations of
convection-driven dynamos in relatively thin rotating spherical shells that
show a transition from an strong non-oscillatory dipolar magnetic field to a
weaker regularly oscillating dipolar field. The transition is induced primarily
by the effects a stress-free boundary condition. The variation of the inner to
outer radius ratio is found to have a less important effect.

11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph