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Vinz9
05-19-2010, 05:55 PM
Hi,

Do you have any tips for creating rolling clouds for a volcano smoke like in this video ?
http://www.vimeo.com/1963815

I get the rolling effect at the start of the sim when there is no velocity in the grid, when the density gets emitted, the velocity vectors start to build up around the edges of the fluid and it creates the rolling motion.

So the best I can get right now is with high damp, high buoyancy, high swirl, high turbulence on the emitter and high density emission.
This way the high damp resets the velocity grid when there's not much fluid emitted and I get the rolling effect again and again.

But there are holes in the smoke, it's not as continuous as the volcano video.

Thanks a lot for any tips.

Vincent

tokanohanna
05-19-2010, 06:45 PM
Hi,

Do you have any tips for creating rolling clouds for a volcano smoke like in this video ?
http://www.vimeo.com/1963815

I get the rolling effect at the start of the sim when there is no velocity in the grid, when the density gets emitted, the velocity vectors start to build up around the edges of the fluid and it creates the rolling motion.

So the best I can get right now is with high damp, high buoyancy, high swirl, high turbulence on the emitter and high density emission.
This way the high damp resets the velocity grid when there's not much fluid emitted and I get the rolling effect again and again.

But there are holes in the smoke, it's not as continuous as the volcano video.

Thanks a lot for any tips.

Vincent


Hey Vincent,

The Volcano test on vimeo you posted is very doable. I would suggest utilizing "All Grids" under the "High detail Solve" tab. This will generate the curls and detail you are looking for in the smoke. If you are noticing your voxels getting a bit aggressive...then use some damping. The rest of your work flow seems fine. Post some tests. Would like to see if I could help any further. I did a test similar to the reference you posted. http://www.vimeo.com/10369823

If you wanted more detail.....you could add temperature turbulence. This will add turb to the temperature not the density giving you some nice detail. Using high turbulence on your emitter is great for breaking up emission, but as the voxels move away from the emitter it will lose the turbulence it inherited over time. Having a good amount of res may help as well.

Vinz9
05-20-2010, 07:01 AM
Hey, great tests you have made!
thanks for the quick answer

I see you are also using temp and fuel, are they necessary to get the rolling motion ?
I understand fuel gets turned into temp which drives the motion of the density, but not really sure how.

I was only using density and velocity grid for now, will do some more tests.

tokanohanna
05-20-2010, 06:53 PM
Hey, great tests you have made!
thanks for the quick answer

I see you are also using temp and fuel, are they necessary to get the rolling motion ?
I understand fuel gets turned into temp which drives the motion of the density, but not really sure how.

I was only using density and velocity grid for now, will do some more tests.

Absolutely.....Setting Temp to Dynamic will allow you to access the temp settings. There you can add temp scale/turb...etc. You should get some nice results.

Temperature is used to ignite Fuel to start a reaction. As the reaction grows, the value of the fuel changes from unreacted (value 1) to fully reacted (value 0). The Help docs really breaks this down further. Take a look.

Vinz9
05-23-2010, 09:22 PM
Ok, spent some more time playing with it, temperature turbulence is the key to the little high freq details.
Still have some problems to have enough emission variation to get the big shapes and not having holes in the smoke! Using a volume field help though.
Not sure about fuel though, if I continuously inject temperature in the sim and keep its dissipation low, it seems to have nearly the same effect than using fuel.

Posted my tests on vimeo : http://www.vimeo.com/11971626

Thanks again

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