Hi,guys

just wonder can I get this kind of shape or not？I tried to figure it out for several weeks。。。but not get the result I want（always getting a mushroom shape on top，I know disturb field can break it，its not what I want）。。。hope someone can help me

Thanks

I'm no sim expert, but to me that feels like you're fighting the core behavior of a volume simulation. If you have a lot of velocity at the leading edge, the solver will try to balance those forces so pressure is maintained, which generally means ‘pushes become swirls’.

You could try lowering your velocity and let the overall sim run slower and calmer, then speed it up afterwards, or think of a way of getting that effect without velocity, ie you emit from a shape at the leading edge of the smoke shape you want, have it follow a curve, only injecting density.

Or not use sim at all, get the shape you want with lots of particles which won't have that pressure balance behavior (called project-non-divergence), and convert it to volume afterwards.

Here is a long thread on combatting mushrooming: https://forums.odforce.net/topic/18397-get-rid-of-mushroom-effect-in-explosion-and-add-details-in-the-opening/ [forums.odforce.net]

mestela
I'm no sim expert, but to me that feels like you're fighting the core behavior of a volume simulation. If you have a lot of velocity at the leading edge, the solver will try to balance those forces so pressure is maintained, which generally means ‘pushes become swirls’.

You could try lowering your velocity and let the overall sim run slower and calmer, then speed it up afterwards, or think of a way of getting that effect without velocity, ie you emit from a shape at the leading edge of the smoke shape you want, have it follow a curve, only injecting density.

Or not use sim at all, get the shape you want with lots of particles which won't have that pressure balance behavior (called project-non-divergence), and convert it to volume afterwards.

Thanks mestela,its so kind of u to reply me when I think this thread will sink into the oceanXD.
And ,yes,I try your idea that particles can bring me beautiful thin detailed smoke,but not thick detailed smoke(or maybe I just missed the right way?).Following another advice u suggested,I lower the velocity and add a little divergence,it seems work sometimes.

mrCatfish
Here is a long thread on combatting mushrooming: https://forums.odforce.net/topic/18397-get-rid-of-mushroom-effect-in-explosion-and-add-details-in-the-opening/ [forums.odforce.net]

Thanks mrCatfish,quite long threadXD.It seems to need some knowledge about solver build up?My mother language is not English..So its a little hard to understand it,but I will try.Thanks again.

Hi! Matt is right.

It's quite easy to do if you need specific shapes and if you are not speaking about a generic smoke simulation and the classical mushroom look. Works very well to do first a particles simulation and source the smoke from them.

How I would do it:
First particles simulation with particles exploding or following the path you want. These are going to be leading particles

Second particle simulation. These particles are sourced from the first simulation. The number is not important but should be enough to fill the “tip” of your smoke spikes.
After this simulation you need to:
- lower the velocities at the tip of your spikes (also close to zero is ok)
- set the density as you prefer
- set to zero the temperature at the tip of your spikes, or very close to it. Smoke will get no bouyancy so it will not move much / not create “mushrooms”

Closer the temperature and velocity will be to zero and closer the simulation will be to the shape of your spikes.
What I usually do is set vel and temperature to zero when they are born and then gradually mix them with their normal value when the particles are close to their death (basically @age/@life as control for the mix).

Finally convert the particles and their attributes to volumes and simulate your smoke.