Flip Fluid odd behavior

[cristiandrade]

Hi there!

I'm learning Flip Fluids with Houdini Apprentice 16 and I did a simple test. It' just an animated character (from Mixamo) rolling over the water. But oddly the fluid start behaving in a strange way, both in the direction of the fluid and velocity, in slow motion, almost anti-gravitational way. Someone may know what could be causing this? Using only shelf tools.

 

Thanks!

 

 

roll.mp4

roll_water.hipnc

[ThomasPara]

Seems like scene scale issue. Your character is around 100 meters high. So your waves are extremely big and therefor it seems like they move in slow-motion.

[lukeiamyourfather]

Scale is critical for getting believable motion. One Houdini unit is equal to one meter for dynamics simulations.

[cristiandrade]

Thanks ThomasPara and lukeiamyourfather. You're right. I didn't realize that the character was so big.

I started over the scene with the character scaled down. The Flip tank is much much smaller know. The only problem is that now I get the message "dop cook. Solving: GAS_BuildCollisionMask". It's taking sooo long to simulate now, it's almost freezed in this cooking process. Do you know how to speed that up?

Thanks for your help, I appreciate your assistance.

Edited May 2, 2018 by cristiandrade

[cristiandrade]

In the end I get back to the old setup, with the big scale, and adjusted the gravity, so now the simulation is much more fast. Still trying to fine adjust the liquid behavior, but I think that's working better at a bigger scale. Don't know if is wrong to work this way or to what kind of problems working like this could lead to.