3 replies to this topic

[kleer001]

I'm probably missing something easy, but here's my setup:
I have a dozen small balls dropping down onto a tub of FLIP fluid. The balls have a radius of .25 and a density of 0.00001 . My Flip fluid has a density of 1,000,000 and a viscosity of 10,000,000.
And yet when I drop the balls into the fluid they drop to the bottom. Wtf? Shouldn't they float on top? Is the illusion of surface tension messing me up?

How do I get RBD objects to float on FLIP fluids?

See attached Houdini 12 file for the cause of my tears.

Attached Files

•  bouyancyTest_01.hip   1.14MB   63 downloads

[kleer001]

Got it!
Go to the FLIP solver -> Solver (tab) -> Feedback Scale

Also, I didn't actually have the viscosity and density on my emission object. Facepalm.

[johner]

kleer001, on 24 May 2012 - 01:46 PM, said:

Got it!
Go to the FLIP solver -> Solver (tab) -> Feedback Scale

Also, I didn't actually have the viscosity and density on my emission object. Facepalm.

Glad you found that.  There's certainly an argument that Feedback Scale should be non-zero by default.

With Feedback having an effect you might dial down some of the physical settings you have.  Very dense and very light objects interacting are a recipe for simulation instability.

[kleer001]

AND... use RBD for your rigid solver engine. Bullet will just drive you nuts.