Flip Fluid collapsing in Bowl.

[richard_mcd_green]

Hi,

(Disclaimer, still pretty new to houdini)
I have a flip simulation that's intended to be a bowl of milk. I want the bowl to be full and to just settle until it's affected by outside forces, but the fluid just instantly collapses to a fraction of it's overall size, even with gravity off it just compresses in on itself. I've tried reading up on this problem online, and have tried various solutions such as disabling reseeding and enabling separation, increasing and decreasing the particle separation and grid scale, but nothing seems to work.

Would someone mind looking at my file and telling me what i'm doing wrong? It's driving me up the wall and it's preventing me from completing class projects.

Thanks,

Richard

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[woodenduck]

Don't have Houdini open right now, but I would first suggest to investigate your collision geometry. Check 'display collsion geo' on the bowl in dops. Make sure it hasn't created a convex hull which encloses your fluid from the start. This would cause undesired results. You may need to switch it to concave. But as I said, I'm not able to open your scene right now, so this is just a guess. 

Cheers, 

WD

[vtrvtr]

Scene collapsing is pretty common. The problem is basically that you don't have enough particles, so they "succumb to their own weight". Possible solutions are: 

1. Add more particles

2. Turn the substeps up

3. Turn up the particle scale

4. If you're on 16 you can try the new "Fill Volume" something in the flip solver, as well the "waterline" options (although now looking at your scene I know this wouldn't work unless you change it)

Mind you that 1) and 2) will increase sim and render times significantly and 3) will probably make you flip look "bloby" 

Now, that aside, take a look how you collisi on mesh looks 

Not quite what it's supposed to be, right?

Now with some collisions from vdb, it looks like this

Also, the way you're making your particles isn't wrong, but it's a bid hard to work with because your particle separation and your scatter aren't really connected. By using a points from volume sop you can match them. 

And that's it

 

 

 

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[richard_mcd_green]

Thank you so much for taking the time to look at this! This is really detailed and useful!