Foam: Surface Lock

[Joelaff]

Does Foam Surface Lock cause the foam to stick to (for instance) the "surface" of the liquid that is against the side of a drinking glass full of liquid? Or does it just apply to the top surface level?

I am getting some foam on the inside of my glass that I do not want, and I am trying to figure out where it is coming from.

Thanks.

[Svetlin.Nikolov]

Ah, this applies to the surface of the liquid. The Sticky Foam on the other hand is the option that can make the foam attach to geometries.

Could it be that there is B2B pushing the foam through the geometry?

[Joelaff]

Thanks for the reply.

Interesting, I do have slightly higher B2B (320). I also have some size variance.

What would I need to do to limit the foam catching in the geometry in this case? Higher resolution sim? I have 9 million cells on the glass.

I animate the surface lock and stick foam to zero during the sim. This seemed to help some, but some foam still remained stuck to the glass. Maybe it was splashes, because it looked like it continued to emit more foam (foam on hit?). I thought I turned off everything except splashes and didn’t see any there, but maybe I had detail reduction on. Will have to re-check.

Right now some animated foam shader Size by age seems to have it looking pretty good. I would be interested in any more suggestions, though.

If I animate sticky foam to zero should this release the already stuck foam? Or would it only prevent new sticking? It didn’t seem to release it. Might be nice to have some way to do that. Maybe I look at the Phoenix properties for the glass.... not sure...

Thanks again.

EDIT: Yes! B2B must have been pushing the particles into the glass. I added a particle tuner to delete particles that were < 0.001 from the glass AND at least a quarter second old AND had a slow Z velocity and it worked. It was a weird looking thing. The particles were stuck in place, but still being moved about by the adjacent velocity of the liquid, but they weren't affected by the foam rising.

[Svetlin.Nikolov]

Hmmm, I'm afraid it could be many things. What I would do - would make sure using the preview that these are the foam particles indeed. Then I would start turning foam options off one by one and simulating after each change, while the resolution is fairly low (9 million should not be very slow). To speed up the iterations, I would shrink the grid along one axis if possible and the issue still reproduced with the smaller grid. This would reveal which option is to blame and then there would be two questions left - how to work around the issue and is this a bug that requires a code change. For the latter we would need the scene though.

Cheers!

[Joelaff]

Not sure if you saw the edit above, but it seems that I solved it by using a Particle Tuner to delete the particles that get stuck from B2B.

"Yes! B2B must have been pushing the particles into the glass. I added a particle tuner to delete particles that were < 0.001 from the glass AND at least a quarter second old AND had a slow Z velocity and it worked. It was a weird looking thing. The particles were stuck in place, but still being moved about by the adjacent velocity of the liquid, but they weren't affected by the foam rising."

I've been through that trouble shooting method a bunch of times It was your comment about the B2B that got me trying to delete the particles.

They were indeed foam particles, and they showed up with every special option turned off.

I do have B2B around 320, also I have foam amount set quite high (400). I wonder if the B2B combined with the number of foam particles generated (high foam amount) perhaps causes the particles to go into the glass (ice cubes too). Maybe there needs to be another check to be sure new particles are always spawned inside the liquid??

[Svetlin.Nikolov]

Ah yes, birth is okay, but I gotta double check if B2B would not push particles to cross into solids. I have a list of a few other things I don't like about B2B at the moment that I wanna change, so this task is starting to weigh more heavily...

[Joelaff]

Ah yes, birth is okay, but I gotta double check if B2B would not push particles to cross into solids. I have a list of a few other things I don't like about B2B at the moment that I wanna change, so this task is starting to weigh more heavily...

Might be nice to have some variance for B2B as well. I find if I turn it up too high the bubbles start to look like marbles bouncing around. However, I want it that high to get the support of the stack of bubbles. I wonder if some variance might help that, or some elasticity setting of some kind.