Jump to content
ashu_tosh_m

Divergence Field cause hole in smoke simulation

Recommended Posts

I was trying to expand the some smoke simulation using divergence field.

the divergence field  create a big hole in the smoke simulation.5e85e6fda06f9_Screenshot(98).thumb.png.266f86a3ef124d96c5eba050f34c9d5b.png5e85e7632df2f_F__HoudiniProjects_REBELWAY.hiplc-HoudiniFX17.5.22902-04-202018_53_01.thumb.png.71630144c106bc8f609dc5d16ac6dd9f.png5e85e7632df2f_F__HoudiniProjects_REBELWAY.hiplc-HoudiniFX17.5.22902-04-202018_53_01.thumb.png.71630144c106bc8f609dc5d16ac6dd9f.png

any idea why is this happening

Test Smoke.hiplc

Share this post


Link to post
Share on other sites

I think divergence needs to be negative. Try changing your keyframe value from 20 to -20.

Share this post


Link to post
Share on other sites
6 minutes ago, Atom said:

I think divergence needs to be negative. Try changing your keyframe value from 20 to -20.

its still creating hole after changing value to -ive

Share this post


Link to post
Share on other sites

Hmm... That's Od. (rewind to clear old cache..?)

Here is negative divergence using your scene. I made the attraction point, bigger and visualized it.

smoke_divergent.gif

Edited by Atom

Share this post


Link to post
Share on other sites
6 minutes ago, Atom said:

Hmm... That's Od.

Here is negative divergence using your scene. I made the attraction point, bigger and visualized it.

smoke_divergent.gif

can u share this hip file?

Share this post


Link to post
Share on other sites
44 minutes ago, Atom said:

I think divergence needs to be negative. Try changing your keyframe value from 20 to -20.

Ops i made the value from 20 to -20

not from  0 to -20 :-|

thats why i was creating a hole !

Thank You sooo much :-)

Share this post


Link to post
Share on other sites
14 minutes ago, Atom said:

Hey its working but i want to expand the smoke.. its looking like the divergence field is attracting the smoke ..

how to expand the smoke.. I want to make something like this....

look how the smoke got expanded  in this video..

 

 

 

Edited by ashu_tosh_m

Share this post


Link to post
Share on other sites

A lot of that look is determined by collision objects. Add a ground plane and make your velocity point down.

You can check out my fuel based rocket launch thread here.

 

Share this post


Link to post
Share on other sites
1 minute ago, Atom said:

A lot of that look is determined by collision objects. Add a ground plane and make your velocity point down.

You can check out my fuel based rocket launch thread here.

 

BTW I'm not making rocket launch smoke.....

i want to learn how that guy has expanded the smoke.

Share this post


Link to post
Share on other sites

If you want to make smoke expand, source a scalar field with positive values like you'd source any other field (density, etc), and set the destination field to "divergence".

If you're getting holes inside, consider adding more density into the area that you're expanding.

Edited by toadstorm

Share this post


Link to post
Share on other sites
1 minute ago, toadstorm said:

If you want to make smoke expand, source a scalar field with positive values like you'd source any other field (density, etc), and set the destination field to "divergence".

yes i have done that... its creating hole u can check the screenshot .. or hip file that i had shared..

Share this post


Link to post
Share on other sites

Looks like you're losing density because your divergence scale is enormous, and it's causing the velocities to be too high relative to the time increment. If you increase your max substeps a bit, you should get more accurate results.

Untitled.png

Share this post


Link to post
Share on other sites
Just now, toadstorm said:

Looks like you're losing density because your divergence scale is enormous, and it's causing the velocities to be too high relative to the time increment. If you increase your max substeps a bit, you should get more accurate results.

Untitled.png

u have increased the substep?

may u share this hip file.? 

it will be easy to understand.. bcoz im noob in Pyro

Share this post


Link to post
Share on other sites

It's the same exact file you uploaded. All I did was increase the maximum substeps on the Pyro solver to 4, under the Advanced tab.

Share this post


Link to post
Share on other sites
1 minute ago, toadstorm said:

It's the same exact file you uploaded. All I did was increase the maximum substeps on the Pyro solver to 4, under the Advanced tab.

okay thank you.....

let me try 

Share this post


Link to post
Share on other sites

You can set the Operation of the divergence field to Subtract and the smoke will move away from the divergence field, instead of being drawn in.

 

Upres on right.

smoke_divergent.gif.abca8db581a45567bc489709837f6cc7.gif
 

Animating the scale of the volume might not be the best approach. All that does is increase or decrease the value in the area of the divergence field. To expang and area, you might try want to animate the scale of the divergence field shape at the SOP level and leave the DOP scale set to a constant. That way, when you expand the size from zero and up, the field size area of effect will grow, not the strength.

ap_UPRES_smoke_divergence_040220.hiplc

Edited by Atom
  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×