Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Collisions of HVCs with a Magnetized Gaseous Galactic Disk   We present two-dimensional MHD numerical simulations for the interaction of
high-velocity clouds with both magnetic and non-magnetic Galactic thick gaseous
disks. For the magnetic models, the initial magnetic field is oriented parallel
to the disk, and we consider two different field topologies (with and without
tension effects): parallel and perpendicular to the plane of motion of the
clouds. The impinging clouds move in oblique trajectories and fall toward the
central disk with different initial velocities. The $B$-field lines are
distorted and compressed during the collision, increasing the field pressure
and tension. This prevents the cloud material from penetrating into the disk,
and can even transform a high-velocity inflow into an outflow, moving away from
the disk. The perturbation creates a complex, turbulent, pattern of MHD waves
that are able to traverse the disk of the Galaxy, and induce oscillations on
both sides of the plane. Thus, the magnetic field efficiently transmits the
perturbation over a large volume, but also acts like a shield that inhibits the
mass exchange between the halo and the disk. For the non-magnetized cases, we
also uncover some novel features: the evolution of the shocked layer generates
a tail that oscillates, creating vorticity and turbulent flows along its
trajectory.

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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: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: q-bio