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Collisions extremely imprecise for concave objects #8

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GottfriedHofmann opened this issue Aug 7, 2017 · 13 comments
Open

Collisions extremely imprecise for concave objects #8

GottfriedHofmann opened this issue Aug 7, 2017 · 13 comments

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@GottfriedHofmann
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GottfriedHofmann commented Aug 7, 2017

I created a really simple cup to fill it with Mantaflow liquid. Yet even at resolution of 128 it is impossible:
untitled

Here is the file:
mantacup.blend.zip

@guilliamPL
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Try to recalculate normals and make thicker walls.

@guilliamPL
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But BTW it will be nice to have more control on the collison objects.

@GottfriedHofmann
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Thanks for the advice, recalculating the normals fixed the first problem, but now I have another one: While elbeem manages fill the cup at 128 res:
elbeem

Manta fails:
manta

It would be really nice to be able to use thin obstacle geometry in many situations.

@GottfriedHofmann
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Btw: I also tried adaptive time stepping.

@GottfriedHofmann
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I just did a test - SPH fluid particles also can handle the obstacle. I wonder why FLIP cannot when both the particle based and grid based simulations in Blender manage so?

@sebbas
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sebbas commented Aug 7, 2017

The reason it's currently failing is in fact because of the "thin" walls.
But I see that this is a bit annoying ... I can probably tweak the levelset generation and fix this.

@GottfriedHofmann
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Being able to have simulations with thin obstacle geometry would indeed be awesome 👍

@thunil
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thunil commented Aug 7, 2017 via email

@sebbas
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sebbas commented Aug 25, 2017

Btw I was able to improve the problem a little bit. The cup now fills up. However, it is still possible that some of the faster FLIP particles drip through the obstacle (in the screenshot, you can see this at the bottom of the cup).

As long as this happens, I'll leave the issue open.

screen shot 2017-08-25 at 22 26 19

@GottfriedHofmann
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Yeah currently still a bit of dripping is occuring.

@sebbas
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sebbas commented Nov 16, 2017

You mean with the mantacup.blend example? I found surface thickening and adaptive time stepping fix the issue in that case. Can you post a screenshot with settings?

@GottfriedHofmann
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GottfriedHofmann commented Nov 16, 2017

I tried a new example: https://www.dropbox.com/s/wwy5ik1aaow6i1n/cup.coffee.classy.blend?dl=1

To test, set the domain size to 128. It's only a few droplets that get away...

@sebbas
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sebbas commented Nov 16, 2017

Increasing the thickness value of the cup seems to help in this case. Note that the value doesn't scale with grid size though (not ideal but good for now)

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