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Smoke grenade


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#1 bloomendale

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Posted 13 April 2013 - 08:35 AM

Hi.
I'm trying to figure out nice setup to get smoke grenade type of smoke.
Here is example i'm after:

(from 0:25 especially)

So i need fairly long "tube" of smoke in the beginning with lots of bumps/bulges and then quite abrupt change to buoyant and noise behavior.
Main problems:
http://my.jetscreens...3-pomb-47kb.jpg
-how to get those bumps (green areas). Cranking up turbulence (i'm using speed field as control one) helps a bit but gives artificial look, but i want natural behavior. Is it possible with points used as divergence source?
-how to force smoke to spread in every direction (so wind like force/vel is not an option) while loosing density and adding disturbance (blue areas). I can add divergence and blow these areas up but there is no conservation of quantities in solver so i will have to "dissipate" somehow new density.


What i have done so far (several attempts):
1) created popnet, emitting particles with birthrate modified in CHOPS to be wave-like. Use this as density/vel source + advected in dops and blended from popnet to fully advected velocity over life - so my particles start controlled by popnet and became fully advected later. Even added them as divergence source to spread and make smoke denser.

2)similair to 1) but don't advect particles. Added curve as velocity source to point smoke to the side and then up. masked out source point to not disturb it much with shaping tools (turbulence, disturbance)

Is it more like voxel-count problem, so i have to sim for a week and all will be fine with just simple setup - like emitting noisy particles from point. Or is it possible to create "bumpy" smoke with medium grids and times?

And what do you think about right setup for such smoke as in video?

thanks in advance.

#2 Netvudu

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Posted 15 April 2013 - 01:24 AM

why isn´t wind an option to blow in every direction? In my experience, a wind Force with no direction and just noise does spread in every direction in a rather interesting manner.

#3 bloomendale

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Posted 15 April 2013 - 06:01 AM

Thanks.
But i'm not about noise field to disturb smoke - this is #2 task)
i'm more about how to get this type of motion with clearly visible small "bumps" everywhere.
http://static3.depos...dense-smoke.jpg

Is it possible to get them without siming giant grids? Cause even without overcomplicating with divergence from points etc and just siming with combustion tends to give big details (bulges, bumps) and not tiny one. Is it about resolution of vel field only or i should use some magic here?

I know i can emit points on surface of density field, add divergence, cool temperature down and buoyancy will do the rest. but it works fine with big plumes going straight up (or to the side but slowly). But i need it in every direction and quickly.

Thanks in advance.




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