Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Pencil Code, a modular MPI code for partial differential equations
  and particles: multipurpose and multiuser-maintained   The Pencil Code is a highly modular physics-oriented simulation code that can
be adapted to a wide range of applications. It is primarily designed to solve
partial differential equations (PDEs) of compressible hydrodynamics and has
lots of add-ons ranging from astrophysical magnetohydrodynamics (MHD) to
meteorological cloud microphysics and engineering applications in combustion.
Nevertheless, the framework is general and can also be applied to situations
not related to hydrodynamics or even PDEs, for example when just the message
passing interface or input/output strategies of the code are to be used. The
code can also evolve Lagrangian (inertial and noninertial) particles, their
coagulation and condensation, as well as their interaction with the fluid.

15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex