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Problem with collision of simple object with flip fluid

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Jesper Rahlff
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Hi guys.

I am working with a flip fluid from object, but I can't seem to get it to collide properly.

I have tried a great number of various things but I cannot make it work.
I have only been working in houdini for 4 months now, so it might be that I have missed some important step.

I have attached a very simplified version of my scene, and in this scene I cannot get the collision to work.

Any help would be greatly appreciated.

Cheers

Attachments:
SimpleBottleTest.hipnc (2.1 MB)

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tamte
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to get proper collisions, your bottle needs to have proper collision volume

you can tweak it in your Static Object in Collisions/RBD Solver/Volume Tab
make sure Use Volume Based Colision Detection is checked
to preview it check Collision Guide
and keep increasing Uniform Divisions until collision volume doesn't have any unwanted holes

since H14 there is nice shelf tool called Deforming Object, that will create SDF VDB volume for your object and Static Object in DOPs for you
for non-deforming objects you can just uncheck Use Deforming on that Static Object
the advantage is that volume generated using VDB is much faster to compute so it makes it easier to tweak (of course it's a big advantage for deforming geometries)

Attachments:
simplebottletest_fix.hipnc (3.2 MB)

Tomas Slancik
FX Supervisor
Method Studios, NY
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Jesper Rahlff
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Thanks so much for the reply. I was not aware of this node.

So this node automatically turn my polygon geometry into a volume collider object?

hm even with this node I can't get it to work. All my particles still seems to disappear, when they hit the bottom of the Collider
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Jesper Rahlff
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When I remove the Groundplane, which was what collided on the bottom of the bottle the particles leak out.

My bottle will have animation on it, and be lifted from the ground place in my scene.

I have attached quick 50 frames of two test I did. one is where the divizion size is 00.1 and the second one is your file without the ground plane at 0.05. and when I look at the collision detection geometry, it shows no wholes what so ever.

Any suggestions to what is wrong?

Attachments:
Bottle_test_Collider2.mov (599.6 KB)

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tamte
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there are actually still some holes at 0.05

but even if volume resolution of your static mesh is already without holes, this volume si being resampled into FLIP collision field which takes resolution from FLIP/Properties settings
so your FLIP collision field may still contain holes
you can visualize it in Guides tab

the easier option than increasing collision volume resolution is to add a bit more thickness for your collision geometry

Attachments:
simplebottletest_fix2.hipnc (3.2 MB)

Tomas Slancik
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Method Studios, NY
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Jesper Rahlff
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Thanks so much for your time and help
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