OpenFOAM(for “Open source Field Operation And Manipulation”)  is а free C++ toolbox for the development of customized numerical solvers, and pre-/post-processing utilities for the solution of continuum mechanics problems, including computational fluid dynamics (CFD).It is released as open source and developed primarily by OpenCFD Ltd since 2004. It has a large user base across most areas of engineering and science, from both commercial and academic organisations. OpenFOAM has an extensive range of features to solve anything from complex fluid flows involving chemical reactions, turbulence and heat transfer, to acoustics, solid mechanics and electromagnetics.

versions 2.3; 4.0
license GNU General Public Licence
website OpenFOAM website
help user guide, tutorialresources