Ring pyro burst

[caskal]

Hey guys,

I have to make a pyro sim of a ring turning into a burst, and then follow a curve and get sucked.

First thing I'm trying to discover is how to get the explosion following this reference:

My first thought is having particles rotating and use that as density source with some disturbance and dissipation, on my first RD I used some particles exploding outwards but the result isnt there:

Any ideas to get to the explosion on the reference? and if there are ideas for the next step > follow curve and dissolve on left, more than welcome.

Thanks!

[caskal]

Another idea was using a cross product on volume gradient to get the motion:

But again not there, maybe a pop curve force with orbit? is this the proper way to go for an explosion like this?

Cheers

 

[Feather]

Your first sim looks pretty promising actually. You would get a lot closer to your desired initial poof using the combustion model rather than just straight smoke. 

Try using the first exploding points as a fuel and temp source for the combustion model and just limit your gas expansion so it doesn't get too out of control. 

[Atom]

Try the surface project, non-divergent, applied to a torus.

http://www.tokeru.com/cgwiki/index.php?title=HoudiniDops#Pyro_stick_to_surface_with_project_non_divergent_sop

[caskal]

Hey @Feather thanks for the advice, did that and i think is getting closer. Now I'm trying to figure out some weird density that doesnt follow the curve after the explosion

Any thoughts on what can be causing this?

 

@Atom thanks for the good ol' wiki help, gonna check that now.

 

Cheers!

[Atom]

It's hard to say, without seeing the hip file. Are you deriving velocity from normals? Some times, the last point on a path can go astray. That last point of the circle, may have a normal pointing in the wrong direction, thus causing the velocity to head off in the stray direction..?
If you are using a Gas Curve Force, once it reaches the end of the path, it continues in the last known direction.

 

Edited October 21, 2019 by Atom

[caskal]

Hey @Atom 

Attaching hip file, would be super helpful if you take a look, been struggling with this for 2 hours.

For the velocity, I did a curve, polyframe N > vel. Didn't use gas curve force.

I tried some stuff like:

• Using negative sink as velocity with no luck. Adding more dissipation affects the overall smoke but not that density artifact 
• Checked all fields separatedly to see if some weird stuff was staying there
• Adding more res to both container and vel particles with no luck, also tried taking off the gasresize
• Deleting particle source, playing with velocty modes and stopping density

Thanks!

ring_density_issue.hip

[3dome]

Hey caskal,

seems like it has to do with a bit of fuel remaining down there and since there is still temperature high enough to ignite it you get a little bit of smoke. 
Increase the burn rate to 1 and it should be fixed.

Edit: you could also play with the Ignition temperature, in this case raise it. Both methods will change the sim a bit, didn't compare it or anything but would guess that increasing the burn rate has less of an impact.
Yet the temps you source into the sim are also quite high, so combustion happens quickly meaning overall temp in container will rise fast and "compensate" for the increased ignition temp. It's just some voxels of fuel will not be ignited instantly anymore but a few frames later (depending on the temperature released from combustion obviously)

 

Edited October 21, 2019 by 3dome

[caskal]

17 minutes ago, 3dome said:

Hey caskal,

seems like it has to do with a bit of fuel remaining down there and since there is still temperature high enough to ignite it you get a little bit of smoke. 
Increase the burn rate to 1 and it should be fixed.

Edit: you could also play with the Ignition temperature, in this case raise it. Both methods will change the sim a bit, didn't compare it or anything but would guess that increasing the burn rate has less of an impact.
Yet the temps you source into the sim are also quite high, so combustion happens quickly meaning overall temp in container will rise fast and "compensate" for the increased ignition temp. It's just some voxels of fuel will not be ignited instantly anymore but a few frames later (depending on the temperature released from combustion obviously)

 

Hey @3dome

Thanks a lot for the tips! I was getting crazy playing with the density source and tweaking the custom velocity with no luck.

Playing with these parameters now seem to fix that density artifact.

Thanks guys!