After you create your nParticle object and set up your effect, you can begin the simulation by playing back your scene. The Maya Nucleus solver performs the simulation, computing all the parameters and settings for all of the objects in its system.
Caching can play a key role in simulation. A cache file stores all position, velocity, dynamic, and render data for your nParticle simulation. Having a cache reduces the number of calculations Maya performs when playing back or rendering scenes because the cached simulation data can be read from disk, instead of being dynamically computed. Rendering from an nCache is system independent, meaning that you can render an nCache that was created on a different system platform and achieve the correct simulation results.
There are different approaches to caching nParticles. You can have a series of cache files containing data for each frame or you can have one cache file that contains all the data for all the frames of your nParticle object’s simulation.