PEDSIM is a microscopic pedestrian crowd simulation system. The PEDSIM library allows you to use pedestrian dynamics in your own software. Based on pure C++/STL without additional packages, it runs on virtually every operating system. The PEDSIM Demo Application (Qt) gives you a quick overview of the capabilities, and is a starting point for your own experiments. PEDSIM is suitable for use in crowd simulations (e.g. indoor evacuation simulation, large scale outdoor simulations), where one is interested in output like pedestrian density or evacuation time. The quality of the individual agent's trajectory is high, PEDSIM can be used for creating massive pedestrian crowds in movies. Since libpedsim is easy to use and extend, it is a good starting point for science projects.
Meep is a free finite-difference time-domain (FDTD) simulation software package to model electromagnetic systems. It supports distributed-memory parallel simulations, nonlinear, anisotropic, and dispersive media, PML absorbing boundaries, and 1D/2D/3D and cylindrical problems. It is completely scriptable from either C++ or a Scheme (GNU Guile) interface.
GarlicSim is a platform for writing, running, and analyzing simulations. It is general enough to handle any kind of simulation: physics, game theory, epidemic spread, electronics, etc. GarlicSim aims to eliminate the need to write any boilerplate code that isn't directly related to the phenomenon you're simulating. GarlicSim defines a new format for simulations, called a simulation package and often abbreviated as simpack. The simpack contains all the code that define the simulated system, and is simply a Python package which defines a few special functions according to the GarlicSim simpack API. Simpack code may also be written in C. All of the tools that GarlicSim provides can be used to run simulations of all kinds of different domains.
openEMS is an electromagnetic field solver using the FDTD method. It employs a fully 3D Cartesian and cylindrical coordinate graded mesh. Matlab (or Octave) is used as an easy and flexible scripting interface. Advanced Features include: multi-threading, SIMD (SSE), and MPI support for high speed FDTD.