Flip sim with one sided collisions

[Waasha]

Hello everyone!

I'm about to start on a new project, where I need the Flip fluid to get "inside" of an object (after floating around it for some time) and collide from within with it. Is there a way to achieve this with volumes?

 

I always use the static RBD with VDB sample collision geo, but I'm afraid it will cause problems, since when the fluid will be outside the object, it will be "inside" of its collision (hopefully that makes sense )

 

As I said, I will try to solve it myself, but if anyone of you have an idea, how to do it theoretically, it would give me a nice headsup

 

Bye, thanks!

[Waasha]

I ran a few tests and I have an update.. There are multiple options I could achieve the desired effect:

 

1) For my situation all I need is an ability to switch the collision on/off based on an attribute... So I would just sample the collision volume and store 1 or 0 if I'm inside or outside and then switch the collision on/off per particle.

 

2) I tried turning off the "Use Volume Based Collision Detection" on the static RBD object and with the normals facing out, the "polygonal" collision worked perfectly, but with inversed normals the solver deleted all particles on the first frame (which is logical-they are inside the collision). So maybe it would suffice to turn off the deletion of particles inside of the collision obj..

 

3) Maybe I could somehow use the streams layout to affect the sim by the collision based on the groups of particles in different streams..

 

Right now I don't know which one is the best, or how to do any of them, but will keep testing..

 

Thanks for any ideas!