Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SPHYNX: an accurate density-based SPH method for astrophysical
  applications   Hydrodynamical instabilities and shocks are ubiquitous in astrophysical
scenarios. Therefore, an accurate numerical simulation of these phenomena is
mandatory to correctly model and understand many astrophysical events, such as
Supernovas, stellar collisions, or planetary formation. In this work, we
attempt to address many of the problems that the smoothed particle
hydrodynamics (SPH) technique has when dealing with subsonic hydrodynamical
instabilities or shocks. To that aim we built a new SPH code named SPHYNX, that
includes many of the recent advances in the SPH technique and some other new
ones, which we present here. SPHYNX is of Newtonian type and grounded in the
Euler-Lagrange formulation of the SPH technique. Its distinctive features are:
the use of an integral approach to estimating the gradients; the use of a
flexible family of interpolators called sinc kernels, which suppress pairing
instability; and the incorporation of a new type of volume element which
provides a better partition of the unity. Unlike other modern formulations,
which consider volume elements linked to pressure, our volume element choice
relies on density. SPHYNX conserves mass, linear and angular momentum, energy,
entropy, and preserves kernel normalization even in strong shocks. The coupling
between the integral approach to calculate gradients and the new family of
volume elements reduces the so-called tensile instability. Both features help
to suppress the damp which often prevents the growth of hydrodynamic
instabilities in regular SPH codes. On the whole, SPHYNX has passed the
verification tests described below. For identical particle setting and initial
conditions the results were similar (or better in some particular cases) than
those obtained with other SPH schemes such as GADGET-2, PSPH or with the recent
density-independent formulation (DISPH) and conservative reproducing kernel
(CRKSPH) techniques.

11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
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The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
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The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-th