Altair Activate - Altair Activate is an open & flexible tool for rapidly modeling and simulating products as multi-disciplinary systems in the form of 1D models (expressed as signal-based or physical block diagrams), optionally coupled to 3D models.
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
Xcos - Xcos is a graphical editor to design hybrid dynamical systems models.
OpenModelica - OpenModelica – A Free Modelica Environment!
R Lang - R is a free software environment for statistical computing and graphics.
Scicos - a graphical dynamical system modeler and simulator