ingnite smoke with oxygen

[lander]

I'm trying to set up a sim that burns wood with lack of oxygen so that I generates smoke. This smoke will move into a second chamber where I introduce air that will allow the smoke to burn.

Should I set this up as two sims where the first one feeds the second one?
I already tried to have it all in one si but I can't control the burning so it propagate back to the fuel source.

I can draw a pretty picture if would help

[Ivaylo Katev]

the easiest way is to make it with two simulators, the first one releases the "fuel", actually no need to be fuel, and the second simulator uses the first one as source, see the burning liquid scene (the old one).
the second and harder way is to generate pure fuel in a chamber filled with smoke. the smoke is important, because otherwise phoenix will consider the chamber filled with oxygen. there is no separate oxygen channel, it is calculated just like O=1-fuel-smoke.

[lander]

Yes I tried using that scene but you used two sims. one for the fuel and one for the fire?
I tried different settings for the propagate but got no change in the behavior.

clean setup.
I'm now using sim 1 to generate smoke (not sure yet what property I should use. fuel or smoke)
and sim 2 will use sim 1 as source.
Does the temperature of the PhoenixSource in the second sim override the sim temperature if sim 1?
That would mean I could run sim 1 untill I'm happy with the result and then run sim 2 independantly.

I'll run some test and find out.

[Ivaylo Katev]

Does the temperature of the PhoenixSource in the second sim override the sim temperature if sim 1?

yes, it will.
in the two simulation method the first simulation is used just as geometry, no physical properties like temperature, smoke, fuel do matter (except the velocity). for example in the scene burning liquid, the first simulation is a cold gas, but in the second simulation it emits hot fire.

[lander]

couple of questions.
1. I seem to run out of fuel at frame 60. And increasing the fuel value in the source from 1 to 10 didn't make a difference. How do I set it to be infinite?
2. Where do I find the "surface" value stated to be set very low in the documentation regarding cascading setups.
3. If I check Temp, Smoke and Fuel in "Output" I assume they generate the maps needed for the second sim?
4. Are those PhoenixFDTexmaps? I don't see the exported channels as options.

I might have misunderstood the entire setup.

[Ivaylo Katev]

the surface is the surface level of the effects channel. but i think you have misunderstood the idea. the cascade setup is intended to continue one simulation into a different box, when the flux is strongly in one direction.
you need a setup similar to the burning liquid scene, with the difference that you "liquid" is the smoke from the wood.

[lander]

He he yep That didn't work so I now work with the old burning liquid and I'm doing better.
I'm closing in but the "colors and transparency is grayed out on the FuelSim. Is there a way to get it active or do I have to make yet another sim to get the slow burning smoke effect?

[Ivaylo Katev]

no idea how this is possible, you mean the button in the rendering panel is grayed and not active?

[lander]

yes. that is what I mean.
but only for the FuelSim.
FlameSim is ok.
I thought it was since it is a liquid using the temperature. But if I inactivate that I don't get any visible result in the simulation. Nor is the button active.

Hmm. I loaded the burning liquid scene to see if that was the same problem in there. No that one seemed ok
So I loaded my scene and now the button is active and happy.

Not sure what caused this.
I merged the sim from the burning liquid into my scene.
Only adapted the simgrid and the sources.

I'll see if I can re-create this later.

[lander]

Well I ditched that idea. It's not evolving into something that I like.
So I spent a hour setting it up as two independent systems and now I'm getting closer.
Now questions.
1. Is there a way to use clipping planes on a simulation?
It works in the camera view but not in the render.
2. when the smoke travels along a surface I get these artifacts from the grid. Is there a good way to get rid of those or do I simply have to crank the settings way up?
(as if you have smoke passing a glass pipe system)

[Ivaylo Katev]

i think both the problems can be solved with gizmos. ifthe second question is related to renderable surfaces, just use inscribed object voxels mode, this will make the smoke to penetrate the geometry.

[lander]

I get a totally different simulation when using inscribed. Different as in no flames.