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control pyro field for flame thrower

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I'm trying to make some flame thrower fx but have some problems with control such fields like temperature, heat and etc ..

for fx what I make, I wanted to make some fire from dragon's mouth.

It's own scale is big so, I imagined that the fire would be more smaller than this pic I captured.

If I make the fire more smaller, Which parameter should I have to control ?

I thought, Shape tap in pyro solver would be used for controling shape of smoke.

and I changed some parameters on Combustion tab, but I couldn't change shape of fire itself.

Help me and sorry for my English  :)

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Hey there,

Controlling the size of your flames is going to have a lot to do with the size of your sources, and your combustion settings.

Without a bit more info though, it’s hard to give you any specific advice, but you could try lowering the “Gas Released” under the combustion tab to get less expansion. 

If you post a hip file of some sort people can probably give you a little more help. 

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I have a bit of experience with flames. What you want to control for the shape are a few things:

Source of your fuel, how much density is coming out and how fast. Disconnect this resolution from your pyro shape so you have less trouble changing up the pyro resolution.

Simulation:

Cooling Rate / Temperature Diffusion, closer to 1 and 0 respectivly for tighter control in the Shape tab...

Combustion:

Gas Released, as low as possible. This is more for explosions, but it can give you some ooomph.

Burn Rate / Fuel Inefficiency, closer to 1 and 0 respectivly for quicker flames.

Shape:

Disturbance, control tightly with temperature. You'll want to preview this.

And overall: Test, test, test. Pyro is difficult. Work rough to fine, coarse to high resolution. And only on as few frames as possible for look.

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Posted (edited)

All the previous advices are valuable. I would just add that it could be a nice idea to generate through particles/geometry a field to use as threshold for guide your simulation. As kleer said pyro is difficult, that's because there are a lot of values which are all related to each other. You change one of the fields or parameters and you will have a completely different look.

 

The result of course is not random. You can know really well what each parameter does, but is not that easy to have a specific idea of what will be the result will all the values/variables combined. I don't have much experience in Houdini and FX in general as some people here in the forum, but I think that they can confirm that. That's why, when is possible, is not a bad idea to reduce this "randomness". 

 

For example you can create some particles, get the aspect you prefer for the core of the flamethrower and then convert them to a density/vel/temperature field (your choice).

Then you can import this field to the pyro DOP and set this as threshold for your flamethrower. If the current voxel is inside the threshold field, is going to follow the velocity field you generated previously from the particles. If is outside of that, it will obey to the current pyro network rules. See for example the particles I have used to control my sim around 00:10 in the video below

 

 

Edited by Andrea
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Thank you guys, I just made little sphere and tried to change all of parameters as you guys let me know :D 

When I finished , I'll upload at here Thank you very much !!

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This video will be very helpfull for you. towards the end one of sidefx interns is going through a "flame thrower" like project he build and how he controlled it.

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