Wikipedia
OpenFOAM
OpenFOAM (for "Open source Field Operation And Manipulation") is a 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). The code is released as free and open source software under the GNU General Public License. The OpenFOAM name was registered by OpenCFD Ltd in 2007 and non-exclusively licensed to the OpenFOAM Foundation Ltd in 2011.