Blender Fluids simulations current state

General Forums Blender and CG Discussions
#1

Hi,

I’m new to blender and I have watched a few tutorials about fluid simulations (Mantaflow, Flip fluids, etc…) and i was surprised of the LACK of interactivity while building the fluid sim…

basically you open blender -> blindfold yourself -> push all the buttons to create a fluid sim with ZERO feedback on what you are doing then hit BAKE ! -> go for lunch -> comeback and check the sim…ah it’s still baking -> get some coffee -> comeback and check the sim…or not still baking…-> go to sleep…wake up -> Finally ! i got something, only to realize you have particles leaking here and there and the liquid texture is all bloby plus all remaining tweaks to be done, well let’s fix that !, -> blindfold yourself -> push a bunch of buttons -> rinse and repeat…

Final result:

  • a 5-10 seconds of a simple water simulation in a cube (with some obstacles, yeaaah !!)
  • few hours/days to get the right settings.
  • more hours/days baking, baking, baking…
  • even more hours/days rendering…(let’s hope EEVEE can help reduce/negate this step)

Is there something wrong with how Blender handle fluid simulations internally or what ? (I might be wrong), all other DCCs let’s you preview your fluid sim as you tweak the settings and add/remove other types of dynamic objects to interact with the fluid sim before you decide; Ok i like this result now i hit render and let it calculate the sim as it renders, or Bake (ONCE !) then render.

I hope there is some future interactivity with the fluid sim being developed or maybe some already existing addon ?

#2

that’s odd. i’m getting a preview in real time even without baking but it’s the first time i’m using the new fluid sim in blender. maybe it’s a bug. hopefully someone more knowledgeable will be able to help you out

#3

Several of us have had problems with smoke/fire in 2.83.
If you are using this version, give 2.82 a try, maybe you will have better results.

#4

There are options to choose how you want your baking to happen.

Fluid-Bakes
Fluid-Bakes4096×2258 2.69 MB

#5

that “replay” did help with the preview, but i find the whole mantaflow simulation “unstable” with inexplicable results, i couldn’t see any fluid particles until i “randomly” changed the “resolution division” from 32 to 64…all of a sudden i can see all the blue dots inside the sphere, while the bounding box of the cube (domain) disappears, i play the preview fine and stop around frame 40, i move the domain away from the sphere, but the animation is still remembering the previous sim (up till frame 40 where it stops and the rest of the liquid falls down) even tough I’m in replay mode (should normally auto clear the cached frames, and start simulating again to register that the sphere is no longer inside the domain logically…) is there an option to tell blender to calculate the sim on the fly whenever i press play ? or make the “replay” cache mode auto clear itself once you hit play.

Thanks in advance.

#6

Unfortunately I’ve been experiencing the same issues. I get around it by simply changing the “Resolution Division” slightly by one or two divisions to force it to recalculate the sim when I make changes. Hopefully this issue will be resolved in future versions.

#7

So I’ve noticed whenever you make any change to your simulation you have to “free data” and “bake” it again. Also it seems that the cache files are pretty sensitive in Blender. Since the 2.9 update seems a bit more stable. It also has the resumable option now that helps.

Check this channel maybe you can find something that helps: VG Leviathan - YouTube

#8

Thanks for the link, will check it out.