Fluid simulation using over 150 times the amount of RAM "required" for baking?

I would really appreciate it if someone could help me figure out why my fluid simulation attempts are using ridiculous amounts of RAM and crashing to desktop regularly. I’ve tried relatively simple scenes and have the feeling that I’m doing something wrong to cause this since other people seem successful with much more complex fluid sims at higher settings with weaker hardware.

  1. Is the amount of memory required for baking as shown on the Domain settings even remotely accurate?

  2. My system is using over 150 times the amount of RAM that is stated as “required”.

  3. Resolutions of 100 and above cause my system to max out all 16GB of RAM for Blender, which then crashes during calculation and receives a close dialog by Windows. There’s no wait option, closing is the only option (AppCrash).

Troubleshooting steps to date:

  • created new scenes
  • changed cache folders
  • applied transforms
  • different inflow shapes
  • different inflow and obstacle volume types
  • subdivision level 1 with post-sim modifier for higher sub
  • shorter sim times
  • shorter animation frame lengths
  • different real-world sizes

** scene file **

Blender 2.68a
Win 7 64
Core i7 3770k
16GB RAM
240GB SSD with 90GB free
Geforce GTX 670

Blender fluid settings


Blender says 41MB required for baking, but Blender jumps from using 95MB of RAM to using 7.3GB of RAM while baking this simple scene!



Here is a rendering of the scene at the above settings. As you can see, it is very simplistic with only two obstacles in the domain.

http://danielnalbach.com/shared/fluid_00001.png

I guess sometimes you just have to talk something out. After trying all kinds of stuff last night and this morning, I decided to try deleting my floor plane. As soon as I did that and rebaked, memory usage went down from 7.3GB to 185MB!!!

The floor plane was intersecting the domain and was substantially larger in the x and y axis than the domain. I don’t think it was touching any other objects.

Objects that participate in the fluid simulation generally should not intersect the domain. That causes lots of problems. Also make sure scales and rotations on your objects are applied before starting.

Just like Ghostbusters…“Don’t cross the lines, that would be bad.”

What he means is Old Testament, Mr. Mayor, real wrath of God type stuff. Smoke sims coming down from the skies! Forty years of noisy renders! Earthquakes, volcanoes… Fluid simulations boiling boiling! Armature sacrifice, monkeys and cubes living together… mass hysteria!

1 Like