# Sparse pyro solver temperature and buoyancy

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Hey

Has anyone messed about with the ambient vs reference temp in the new sparse pyro solver? My intuition tells me that if the temperature of the smoke falls below the ambient temperature, then in theory the buoyancy direction should reverse and the smoke should sink. This doesn't seem to be happening though, as the fluid cools it stops moving and hangs in space, whereas I want it to start moving in the direction of gravity.

ie. hot smoke rises, cool smoke falls. The falling part is eluding me right now.

M

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If you emit negative temperature values it works as expected, the smoke goes down.
Maybe you want smoke with zero temperature to go down?
if that's the case, there is a "real" ambient temperature setting on the gasBoyancy DOP: /obj/smoke_simulation/pyro_solver/solver/buoyancy/ambient
it's a simple offset on the overall temperature, so you can set where the reference zero temperature is.
also that DOP node has the expression using the ambient and reference temperature, hope that helps.

Edited by bunker
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Yeah I want 0 temps to go down. I normally mess with the real ambient temp in the gasBuoyancy but I was lured into thinking the parm called 'Ambient Temp' would do what it said :D. I see the expression in there, perhaps it's not behaving as I think it should. I'll mess with it a little, thanks!

M

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I also thought it would behaved like that but it seems like it's setup so that ambient temperature = 0 buoyancy. I think sparse pyro needs a masterclass.

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Yeah seems a bit weird. Probably an attempt to solve something with math (tying it gravity?) instead of just exposing the correct parameters. Which is weird if it's supposed to make it simple, because we get a few more parameters that are harder to understand for buoyancy - instead of just having the 3 well known ones (direction, amplitude and ambient).

Delete that expression in Bouyancy Lift on the Gas Buoyancy DOP and use it normally seems to work well.

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Yeah it's definitely a bit esoteric and not simpler, I've always wondered why they don't expose the ambient temperature parm.

Leaving the expression in there and messing with the ambient temperature does some pretty weird things so deleting the expression seems like the way to go for this project.

Thanks!
M

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I've tried spars too and got weird smoke freeze during cooling. Looks like it lost velocity with temperature and I have no idea why.

Maybe it is some bug in setup now, but without full understanding how it works, hard to fix it

Edited by tamagochy

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@tamagochy this seems relates to this post:

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20 hours ago, bunker said:

@tamagochy this seems relates to this post:

I read this topic and not test this yet.

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