Code Saturne
Code_Saturne is a general-purpose computational fluid dynamics free computer software package. Developed since 1997 at Électricité de France R&D, Code_Saturne is distributed under the GNU GPL licence.
It is based on a co-located finite-volume approach that accepts meshes with any type of cell (tetrahedral, hexahedral, prismatic, pyramidal, polyhedral...) and any type of grid structure (unstructured, block structured, hybrid, conforming or with hanging nodes...).

Its basic capabilities enable the handling of either incompressible or expandable flows with or without heat transfer and turbulence (mixing length, 2-equation models, v2f, Reynolds stress models, Large eddy simulation...).
Dedicated modules are available for specific physics such as radiative heat transfer, combustion (gas, coal, heavy fuel oil, ...), magneto-hydro dynamics, compressible flows, two-phase flows (Euler-Lagrange approach with two-way coupling), extensions to specific applications (e.g. for atmospheric environment).

Code Saturne install 

Code_Saturne may be installed on a Linux or other Unix-like system by downloading and building it. No system files are changed, so administrator privileges are not required if the code is installed in a user's directory. Packages for Code_Saturne are also available on Debian and Ubuntu. Alternatively, CAE Linux (latest version CAE Linux 2011), which is based on Ubuntu 10.04 LTS, includes Code_Saturne pre-installed.

A port to Windows systems (built with Cygwin) is not maintained anymore, but the code also works well in the Windows subsystem for Linux.

Interoperability 

Code Saturne supports multiple mesh formats. The following formats, from open source or commercial tools, are currently supported by Code Saturne:

Supported mesh input formats (source):
 SIMAIL (NOPO) – (INRIA/Distene)
 I-DEAS universal
 MED
 CGNS
 EnSight 6
 EnSight Gold
 GAMBIT neutral
 Gmsh
 STAR-CCM+

Supported post-processing output formats
 EnSight Gold
 MED
 CGNS

Alternative software 
 Advanced Simulation Library (open source software AGPL)
 ANSYS CFX (proprietary software)
 ANSYS Fluent (proprietary software)
 COMSOL Multiphysics
 FEATool Multiphysics
 Gerris Flow Solver (GPL)
 OpenFOAM (GPL)
 Palabos Flow Solver (AGPL)
 STAR-CCM+ (proprietary software)
 SU2 code (LGPL)