Smoke from scratch, add force

[fabsberry]

Hey dudes,

I'm trying to build a simple smoke solver from scratch to understand more how they work. I created a simple setup with density, temperature and buoyancy.

Now I want to add a second velocity volume as a force to my simulation. 

But when I add the force, the velocity is increasing massively in a few frames. I have to mix my force with the existing velocity but I don't understand how to do this 

 

 

 

my_solver.hiplc

[fencer]

Maybe you forget "Gas Project Non Divergent", check this:

 

Edited December 11, 2019 by fencer

[Drughi]

16 hours ago, fabsberry said:

But when I add the force, the velocity is increasing massively in a few frames. I have to mix my force with the existing velocity but I don't understand how to do this 

To do this the right way take a look into the gas wind. The quick and dirty way is to simply advert the fields with you force, but this is not recommended, because it leads to wrong velocities.

Edited December 12, 2019 by Drughi

[Drughi]

my_solver.hipnc

[fabsberry]

Thank you, Johannes! The gas wind node was a great hint.

I found an additional mistake that I made: the border type of my fields was set to streak but it had to be constant.

 

my_solver_fixed.hiplc