While FumeFX already has a rich set of parameters to control simulations, these parameters affect each voxel in the grid equally. With Effectors, users have total control to affect virtually each voxel with its own set of parameters. Effectors enable users to control parameters such as Gravity or Vorticity in each voxel based on input data ( eg: velocity, smoke, 3d map ).
With Effectors you can achieve effects that were impossible to do before. In this video, the Gravity parameter is connected to the Effector. The upper half of the FumeFX grid has inverted gravity which results in the smoke to stabilize on the gravitational boundary.
Effector connected to the Gravity parameter
For example, it is fairly simple to locally control the vorticity parameter based on the voxel velocity, or to set smoke color based on the velocity. In the animation below, Effector becomes active at frame 50 and it set smoke buoyancy parameter locally.
Local adjustment of smoke buoyancy
Not only the simulation parameters can be adjusted on the per-voxel basis, but also each field itself. For that purpose, each channel (eg: Smoke, Temperature) have Master Effector slot that can have mutliple Effectors assigned.
Effectors are the ultimate tool for an advanced FumeFX artist.