MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
OpenFOAM - OpenFOAM® - Official home of The Open Source Computational Fluid Dynamics (CFD) Toolbox.
OpenModelica - OpenModelica – A Free Modelica Environment!
Xcos - Xcos is a graphical editor to design hybrid dynamical systems models.
SimFlow - SimFlow is a powerful CFD software, focused on engineering and science.
GNU Octave - GNU Octave is a programming language for scientific computing.