Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Implementing a new recovery scheme for primitive variables in the
  general relativistic magnetohydrodynamic code Spritz   General relativistic magnetohydrodynamic (GRMHD) simulations represent a
fundamental tool to probe various underlying mechanisms at play during binary
neutron star (BNS) and neutron star (NS) - black hole (BH) mergers.
Contemporary flux-conservative GRMHD codes numerically evolve a set of
conservative equations based on 'conserved' variables which then need to be
converted back into the fundamental ('primitive') variables. The corresponding
conservative-to-primitive variable recovery procedure, based on root-finding
algorithms, constitutes one of the core elements of such GRMHD codes. Recently,
a new robust, accurate and efficient recovery scheme called RePrimAnd was
introduced, which has demonstrated the ability to always converge to a unique
solution. The scheme provides fine-grained error policies to handle invalid
states caused by evolution errors, and also provides analytical bounds for the
error of all primitive variables. In this work, we describe the technical
aspects of implementing the RePrimAnd scheme into the GRMHD code Spritz. To
check our implementation as well as to assess the various features of the
scheme, we perform a number of GRMHD tests in three dimensions. Our tests,
which include critical cases such as a NS collapse to a BH as well as the
evolution of a BH-accrection disk system, show that RePrimAnd is able to
support highly magnetized, low density environments, even for magnetizations as
high as $10^4$, for which the previously used recovery scheme fails.

18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
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
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci