Particle System parameter animation
It is not possible to animate particle Emission parameters with keyframes or drivers.
There are many requests for help on this on the blender.stackexchange site ( a , b , c ) and some tips on less effective tricks and kooky workarounds.
My use case is a simple irregular drip of particles over time, as a simplified (inexpensive) alternative to a liquid simulation.
As an aside, it seems odd that there is not blanket ability to animate/driver any and every text parameter in blender.
2 Comments
To me it sounds like the current particles system doesn't work in the way you need to begin with. It emits a fixed number of particles on a fixed time range. What you need is a system that emits X particles per seconds, which would work more in a real time "unlimited" simulation..
Maybe simulation nodes can do that, though?
You could pull something like this off with a spread of particles over a longer time than usual for the sequence. For example, you can move your emitter around quite erratically along the pipe with say 200 particles over 1000 frames, starting at -200 (depending on the lifetime of the first bunch of particles). Using metaballs can have them fuse if a few are close together, plus you can use liquid physics with the particle system.
Thankfully, for your example, there are many ways to make it happen with the current particle system as-is. Plus, most of the particle systems' settings are keyframeable and can be driven. It's only a the few main ones that underscore other calculations that can't such as the emission amount, which is what I'm guessing you want here, hehe.