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Substepping between different DOPnets

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Hey all, I'm trying to get a better grasp of best practices for managing substeps between two separate DOPnets. I have a DOPnet that takes in moving geo and outputs particles, which I rasterize to a volume, then source into another DOPnet as fuel, temp, etc. for a pyro simulation.

What I'm wondering about specifically is how to keep these two DOPnets in sync. i.e. I want to make sure only newly generated fuel is sourced into the pyro sim, not fuel that's already "burned". My concern is that if the POPnet creates particles with life longer than a substep on my pyro sim, they will be copied into the pyro multiple times.

It seems like it would be best if the particles and Pyro were created in the same DOPnet? I don't know enough about how any of this works though. 


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In case anyone else reads this and is wondering the same thing, what I ended up doing is creating my particles in the same DOPnet as my pyro, then sourcing them into my pyro sim by way of a "Gas Particle to Field" node and a "Fetch Data" node. The "Gas Particle to Field" does about what you'd imagine, the caveat being that the particles must already be attached to the smoke object. So the "fetch data" (placed in line between the smoke object and the solver) gets the "Geometry" data from the POP simulation and appends it to the smoke object. Then the "Gas Particle to Field" can be pointed to that "Geometry" data. With a smoke sim I think it's probably okay to leave the incoming particle data named "Geometry", but with a pyro sim you might need to rename it if the sim has some geometry data already. Mine did and I'm not sure why exactly, but it could have been from something else I was doing.

Here's a nice little write up about it: http://www.tokeru.com/cgwiki/index.php?title=HoudiniDops#Advect_smoke_with_particles

Hope this helps someone.

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