One of the many options that you have with FumeFX is that you can use a Particle System as the source of your simulations (as explained in the section of this reference). Particle Flow operators offer a way to control any such particle system over the course of its life. Although Particle Flow is an element of 3ds Max, FumeFX comes with operators that allow you to employ several of its features. These operators are: , , and .
It is highly recommended that you use the Cache operator that comes with Particle Flow; this will help you to avoid any delays caused when PF has to re-compute the particle positions. For example, if you move the time slider one frame backwards without using the Cache operator, PF would have to update the particles starting from the Birth Event's start time. Furthermore, FumeFX would have to load its output for each frame, as well.
FumeFX can immediately affect Particle Flow during simulation, which allows you to track progress in viewport.
The most significant feature is that, through the use of Particle Sources, FumeFX and Particle Flow can dynamically affect each other during simulation! After the simulation is complete, particles can be cached to produce the same behavior as they did during FumeFX simulation.
In order to access these options, you first need to create a Particle System. Then, while the Particle emitter icon is selected, click on the Particle View button that appears in the 3ds Max control panel. In the Depot pane of this window, select FumeFX to access the appropriate controls.