Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Six-moment Multi-fluid Plasma Model   We present a six-moment multi-fluid model, which solves the governing
equations for both ions and electrons, with pressure anisotropy along and
perpendicular to the magnetic field direction, as well as the complete set of
Maxwell equations. This set of equations includes the Hall effect, different
temperatures for different species and pressure anisotropy. It is more
comprehensive than the five-moment equations with isotropic pressures and
significantly less expensive than the ten-moment equations with a full pressure
tensors. Similarly to the five- and ten-moment equations, the wave speeds are
naturally limited by the speed of light, which eliminates the issue of
unlimited whistler wave speeds present in Hall magnetohydrodynamics (MHD). It
is also possible to simulate multiple negatively charged fluids, which cannot
be done in MHD models. The six-moment model is a reasonable description of the
plasma outside magnetic reconnection regions and therefore well-suited to be
coupled with an embedded particle-in-cell model that covers the reconnection
region. Our numerical implementation uses a point-implicit scheme for the stiff
source terms, and we use a second-order accurate Rusanov-type scheme with
carefully selected wave speeds. For the plasma variables and the magnetic field
the maximum wave speed is based on the fast magnetosonic speed of MHD with
anisotropic pressures that we derive. For the electric field related variables
the speed of light is used. The divergence of the magnetic field and Gauss's
law are controlled with a hyperbolic-parabolic scheme. We present a number of
numerical tests to demonstrate that this numerical model is robust without
being excessively diffusive.

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The categories of this paper are: solv-int
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The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
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The categories of this paper are: funct-an
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The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
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The categories of this paper are: stat