Free Fire Dynamics Simulator (FDS) and Smokeview

Fire Dynamics Simulator (FDS) is a large-eddy simulation (LES) code for low-speed flows, with an emphasis on smoke and heat transport from fires.
Fire Dynamics Simulator (FDS) is a computational fluid dynamics (CFD) model of fire-driven fluid flow. The software solves numerically a form of the Navier-Stokes equations appropriate for low-speed, thermally-driven flow, with an emphasis on smoke and heat transport from fires.

Smokeview (SMV) is a visualization program used to display the output of FDS and CFAST simulations.

FDS+Evac is the evacuation simulation module for Fire Dynamics Simulator (FDS). The software is used to simulate the movement of people in evacuation situations. The evacuation simulations can be fully coupled with the fire simulations.

These tools are open source and freely available.

Source: https://code.google.com/p/fds-smv/