If you add more than one Smoke domain in your scene, the first one will not make any smoke.
Is it possible to get more than one simulation in the same scene?
(For example, duplicating the entire scene, baking each simulation in separate scenes, then somehow put them all back.)
How might this be done?
It is possible.
You can create multiple working domains, but the whole process seems a bit awkward and only sometimes works, without any recognizable pattern.
One way I found that seems to consistently work as expected is to create your domains on separate layers.
If you need more than 20 domains, they sometimes work on the same layer, but I have not found what it is that makes/breaks them when they are on the same layer.
Most of the time it seems to work if the one domain that runs in real time is baked first, then the next domain that runs in real time, and the next, etc.
Create domains, on separate layers. Note that Separate domains can share the same Flow objects; however, they will not interact.
Here, each domain is on a separate layer, and each flow object is visible on all layers with a domain object.
Bake each one individually:
It seems that the selected domain is always displayed above the others. Here is the domain that covers all the inflow objects selected (top) and unselected (bottom) so it's more visible that the domains share the same inflow objects:
Blender is limited to simulating one smoke domain.
The way I see to do it is make one large smoke domain surrounding all smoke simulations that you want and use multiple emitter objects. I just tested this with ten smoke emitters within the one domain.
The limitation there would be that each simulation has to use the same domain settings.
You should also be able to render each simulation individually and composite together. Depending on your scene, you may need to make sure you get masking data for objects that would pass in front of the sim.
