TurbulenceFD’s simulation pipeline implements a voxel-based solver based on the incompressible Navier Stokes equations. That means it uses a voxel grid to describe the volumetric clouds of smoke and fire and solves the equations that describe the motion of fluid on that grid. For each voxel TurbulenceFD calculates the velocity of the fluid as well as several channels to describe properties like temperature, smoke density, amount of fuel, etc. This simulation process produces a voxel grid for each frame, which is cached on disk for use by the Volumetric Renderer.
To setup a fluid simulation, the artist uses any type of geometric object or particle system to paint the sources of smoke, heat, fuel, etc. in space. The flow then carries along these emissions in a physically plausbile way that creates the realistic look of fire, explosions, vapor, clouds, dust and much more.