Exploding Foam

[themaxxer]

Hi there
I have a Problem with a Scene i am working on. It's a small River with Foam generated. I don't use Splashes. I tried to lower and raise every Value and resimulated the Scene so often. I changed the Steps per Frame from 1 to 16, i changed the B2B Interaction from 1 to 400, i tried different Bubble Sizes. I tried Rising Speeds from 0 to 80 also i tried Falling Speeds from 0 to 500. Nothing helps!!! The Foam is always exploding. Please Help me.

https://www.dropbox.com/sh/klwrgq1j9...-Nr9qmh8a?dl=0

Kind Regards David

[Svetlin.Nikolov]

Hey,

This usually happens when there are open geometries interacting with the fluid. Are you using any deformed planes and are you sure all the geometry is closed and shelled, with no inverted normals or overlapping faces?

Cheers!

[themaxxer]

Thanky you for your quick answer. That is the last Thing i tried and until know it works better. I collapsed my deformed Mesh, the Stack into a Polymesh. the Normals were not inverted. Do i have to apply a shell modifier to the riverbed? There is also another Problem, when i use Initial Fill Up then there is the whole Mesh displayed for this 30 % it does not cut the Mesh with the Riverbed.

[Svetlin.Nikolov]

Oh, this definitely means you should shell the riverbed and make the shell so thick, that it fills the volume of the simulator entirely, otherwise you will have a second river running under the surface

[themaxxer]

I can't shell such a Geometry. The Shell Modifier doesn't work. It is already a closed Box and i use the right click menu and clicked on Solid Object and Clear Inside. Have you an idea how to shell such a geometry until it fills the volume of the simulator entirely?

[Svetlin.Nikolov]

Ah, okay then, so you have to just extrude it to the bottom of the simulator. This way the initial fill will not create liquid underneath.

[themaxxer]

It doesn't work, it once did. I downloaded the newest nightly build. Can you please look at the scene? Do i do something wrong?

https://www.dropbox.com/s/djtg76gtr2...ERGED.max?dl=0

[themaxxer]

The Liquid is not underneath the Simulator it is inside. I had such Problems with earlier Versions of PhoenixFD. It worked for so long.

[Svetlin.Nikolov]

Ah, thanks very much for the scene! Seems like something is wrong with the way the initial fill up converts liquid particles to voxels and then to mesh. If you enable particle preview you will see that the liquid is correctly created only atop the river bed. However, if you enable liquid grid preview, you'll see that the voxels are created in the entire fillup volume. This is something you'll need for ocean sims where the initial fillup is used most often, but you don't need it here. I'll see how to change that.

In the meantime, you could workaround this by turning initial fillup and using a box with a brush liquid source instead...

Using a latest nightly, do you still have particles flying though? I don't have them here, but if you still do, please ping me.

Cheers!

[themaxxer]

As you can see, there are still these little exploding Chunks of Foam. Do they really behave like this because of wrong Geometry? I tried different B2B Values and Step per Frames.

https://www.dropbox.com/s/gca4362vrq...g_foam.7z?dl=0

[Svetlin.Nikolov]

Oh, let's see then.. The geometry looks great, I think it might be something else that's causing it.

[Svetlin.Nikolov]

Run your scene again with the latest nightly, but still can get the exploding foam. When I've seen such issues, there were two causes - either patterns were on and were too strong, which is not the case for your scene, or it was the B2B. If you lower the B2B to zero, just for the test, do you still get these?

Cheers!

[themaxxer]

I simulated the scene with a finer grid for a few hours. this is the result. i downloaded the newest nightly and will try to simulate without B2B and will send you the movie. The one i send you know is as i said with the nightly from yesterday.

https://www.dropbox.com/s/y88y7nvemq...newest.7z?dl=0

[themaxxer]

this movie is simulated with the newest nightly build. Cell Size is 1.6... Steps per Frame are only 4. B2B is 40. i do know a Simulation without B2B Interaction. It looks like that Highres Sims with a fine Grid and more Steps per Frame then the Foam does not spread as with a Low Sim.

https://www.dropbox.com/s/4oov0r6bp8...ightly.7z?dl=0

[themaxxer]

How important is Simulate Air Effects and Surface Lock? Could this be the Problem? Should i use it or not?