This page contains the reference manual for the Advection tab in the ExplosiaFX object.
Advection of the smoke, heat, etc. is of course already built-in to ExplosiaFX. So what is the purpose of this tab?
If you add an emitter to the scene and if you check the 'Advect Particles' switch, the particles from the emitter will be altered in the same way as the Explosia parameters such as smoke. The particle parameters are directly altered by the relevant channel. For example, if 'Velocity' is set to 100%, the particles take on the velocity in the solver voxels they pass through. This gives very fluid and natural-looking movement to the particles. You can turn off the display in the ExplosiaFX solver if desired, in which case the solver is in effect acting like a particle modifier.
In this video, you can see the particles from an emitter as well as the smoke display; the particles are shaded blue to white. At frame 60 the display is turned off, showing the particles being advected by the solver:
For other channels, the particle parameter is changed in the same way by the voxel value. In this video the temperature channel alters the particle temperature, which you can see if the particle display is set to 'Gradient (Parameter)' and the parameter is 'Temperature':
The tab interface looks like this:
Check this switch to turn particle advection on.
This is a drop-down menu with two options:
In this mode the particle parameter is set each frame with a new value.
In contrast to 'Set', in this mode the parameter change is added to the previous value. This can result in the parameter (such as particle speed) increasing dramatically, which may or may not be desirable.
Smoke, Fuel, Temperature, Velocity, Color, UVW
These settings are the relative effect each of these channels will have on the corresponding particle parameters.
When a source object is an emitter, you can specify which groups are advected by by dragging the particle group objects into this list. If the list is empty, all groups emitted by the source emitter are advected.