Qucs-S is a circuit simulation program with Qt-based GUI
FlightGear Flight Simulator: free open-source multiplatform flight sim
Quantum Mechanical Charge Field - Molecular Dynamics
Parallel simulators for Membrane Computing on the GPU
An Open source Analysis and SImulation Toolbox for Fuel Cells
A highly flexible 3D flocking boids simulator, conceived as a tool for
3D model viewer and world navigator.