Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Penumbral fine structure and driving mechanisms of large-scale flows in
  simulated sunspots   We analyze in detail the penumbral structure found in a recent radiative MHD
simulation. Near tau=1, the simulation produces penumbral fine structure
consistent with the observationally inferred interlocking comb structure. Fast
outflows exceeding 8 km/s are present along almost horizontal stretches of the
magnetic field; in the outer half of the penumbra, we see opposite polarity
flux indicating flux returning beneath the surface. The bulk of the penumbral
brightness is maintained by small-scale motions turning over on scales shorter
than the length of a typical penumbral filament. The resulting vertical rms
velocity at tau=1 is about half of that found in the quiet Sun. Radial outflows
in the sunspot penumbra have two components. In the uppermost few 100 km, fast
outflows are driven primarily through the horizontal component of the Lorentz
force, which is confined to narrow boundary layers beneath tau=1, while the
contribution from horizontal pressure gradients is reduced in comparison to
granulation as a consequence of anisotropy. The resulting Evershed flow reaches
its peak velocity near tau=1 and falls off rapidly with height. Outflows
present in deeper layers result primarily from a preferred ring-like alignment
of convection cells surrounding the sunspot. These flows reach amplitudes of
about 50% of the convective rms velocity rather independent of depth. A
preference for the outflow results from a combination of Lorentz force and
pressure driving. While the Evershed flow dominates by velocity amplitude, most
of the mass flux is present in deeper layers and likely related to a
large-scale moat flow.

13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph