Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 3-D non-linear evolution of a magnetic flux tube in a spherical shell:
  the isentropic case   We present recent 3-D MHD numerical simulations of the non-linear dynamical
evolution of magnetic flux tubes in an adiabatically stratified convection zone
in spherical geometry, using the anelastic spherical harmonic (ASH) code. We
seek to understand the mechanism of emergence of strong toroidal fields from
the base of the solar convection zone to the solar surface as active regions.
We confirm the results obtained in cartesian geometry that flux tubes that are
not twisted split into two counter vortices before reaching the top of the
convection zone. Moreover, we find that twisted tubes undergo the poleward-slip
instability due to an unbalanced magnetic curvature force which gives the tube
a poleward motion both in the non-rotating and in the rotating case. This
poleward drift is found to be more pronounced on tubes originally located at
high latitudes. Finally, rotation is found to decrease the rise velocity of the
flux tubes through the convection zone, especially when the tube is introduced
at low latitudes.

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The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
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The categories of this paper are: cond-mat
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The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol