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Sand Simulation


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I'm a student at NAD in Montreal and I'm trying to learn Houdini.

I have a project in which I need to simulate sand on top of a falling rocks RBD simulation, which is on top of a FEM sim. (The FEM is the deforming ground)

So I cached every collision objects with the CollisionSource node (with 4 substeps to match de grain solver).

Now, if I simulate the sand, it explode on random frames. (see flipbook here: password: sandsim

This is my second attempt and it still explode (at fist I used 10 substeps)


Does somebody have any ideas on what could be the issue?




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After some tests, the problem comes from the animated rocks. Even without animation on the rocks, the sand explode.

In my DOP, I load only 1 cached VDB of all the rocks as a collision object.

I tried to switch from a POP Solver to a FLIP Solver just to see the CollisionGuide of the rocks (how the solver see the rocks) . And it seems fine.


Any ideas?

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Ok, so now I know that

-It's working with static and not cached rocks

-It's NOT working with animated and not cached rocks

-It's NOT working with cached rocks, animated or not

(all tests with no substep)


Now I think that I may need to send to the DOP Network my 800 rocks separately... but how?

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