OpenFOAM - OpenFOAM® - Official home of The Open Source Computational Fluid Dynamics (CFD) Toolbox.
GNS3 - GNS3 is a graphical network simulator that allows simulation of complex networks.
ANSYS Fluent - ANSYS engineering simulation and 3D design software delivers product modeling solutions with unmatched scalability and a comprehensive multiphysics foundation.
ns-3 - a discrete-event network simulator for internet systems
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
NetSim - NetSim software was created to simulate various Cisco systems. Cisco software is known around the world as being one of the best network, routing and switch systems for businesses and private use. Read more about NetSim.