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dyei nightmare

flip + rbd collision, closing the gap?

 have this setup where i have variable density and rbd objects for colision,  anybody knows how can i close the gap where the collision ocurrs?  i mean i want that after the rbd object get into the liquid it closes again,  or fills again the area where collision happen

im in houdini 12.5

i tried gas surface tension  with no luck, for some reason it just colapses the FLIP fluid  and it goes just crazy erratic 

 

file attached here 

SOLUCION.hip

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One thing you can do is activate the Surface (in blue) and Collision (in pink) guides in the Flip Fluid object. You must also turn off the RDB Collision object display or these guide surfaces will not be seen in the viewport  because their volume resides inside the RBD objects and thus is culled from display.


When I altered the display of the AutoDopNetwork in this way, I could clearly see that the sphere is represented ok but the teapot is just a lump. Try activating Collision Separation and lowering it to 0.04.

fluid_collision.gif

Edited by Atom
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In this one I also lowered the particle separation to 0.08. With the collision separation set at 0.04 it presents twice the resolution to the FLIP Solver compared to the fluid itself. Typically these are just linked and that is the default. But if you are happy with the surface and just want more collision resolution, that is how you achieve it.

 

I found this information in Jeff Wagner's video tutorial on FLIP at 19:00 minutes in.

fluid_collision.gif

Edited by Atom
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Unfortunately I don't have access to Houdini 12.5 anymore but, I opened this in 15 and didn't see any issues.

I am uploading the file that worked for me. I did some tweaking in here and cleaned up some stuff. Also turned your rbd resolution down on some of the objects to something a little more manageable..

SOLUCION_RB.hip
 

edit: took out a huge chunk of text because I just got schooled in a part of flip that was unbeknownst to know me. The more you know.

Edited by rbowden
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thanks a lot  guys!!  acctually a new challenge arises...    im getting strange behavior in this simulation with variable density,  one solution is increasing the feedback scale to 1 and set a maximum of 1000 in the flip density,   but not even in this case,  do you know why this fluid is exploding like this?  

whyyyyyyyyyyyyyyyyy.hip

Edited by dyei nightmare

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Before you post a scene that contains referenced geometry CTRL-Click on the lock flag of the File node to embed the geometry in the HIP. Your posted file comes up blank for me because of this reason. When I replace your File referenced .bgeo with basic shapes like box, sphere torus etc.. I don't get an explosion of velocity.

There have been a lot of bugs fixed since Houdini 12.5. If your hardware is capable of upgrading to Houdini 15.5 I would recommend upgrading to it. I think you can also keep Houdini 12.5 as well.

Edited by Atom
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...but im suspecting that for that to work is needed a clean proxy geometry,  ill see what happens

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18 minutes ago, Atom said:

Before you post a scene that contains referenced geometry CTRL-Click on the lock flag of the File node to embed the geometry in the HIP. Your posted file comes up blank for me because of this reason. When I replace your File referenced .bgeo with basic shapes like box, sphere torus etc.. I don't get an explosion of velocity.

There have been a lot of bugs fixed since Houdini 12.5. If your hardware is capable of upgrading to Houdini 15.5 I would recommend upgrading to it. I think you can also keep Houdini 12.5 as well.

yes sorry,   my mistake,   forgot about that,  yes,   i almost confirm that a very clean  proxy geometry for collisions fix this issue,  and complex geometry  needs that proxy geometry

Edited by dyei nightmare

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