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mrWolf

FLIP velocity field peaks

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Hi all,

I am having some weird artifacts in the velocity field generated by a simple FLIP simulation in Houdini 12.1.

Basically the more I reduce the particle separation of the source fluid object to get a higher res, the more I get peaks (1-2 frames max) in the velocity field, popping here and there in the fluid.

 

post-1409-0-49626100-1390268398_thumb.jp

 

It happens mainly on the bottom of the fluid, and that is easy to get rid of.

The problem is that it happens even in other parts of the fluid when some object collides and interacts with the fluid.

 

Now this would usually not bother me cause what happens underwater is rarely visible, but in this case I am implementing a white water generator and those velocity peaks are creating unwanted annoying water foam underwater.

 

I attached a scene file that shows the issue.

Did anyone experience the same issue and solved it somehow ?

water_tank_h12.1_05_odforce_test.hip

Edited by mrWolf

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There was a bug before kinda like this, can't remember which version it was in or when it got fixed though.

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Oh yeah, the hip shows you're using 12.1.125 - newer version highly recommended!

(If you're locked to 12.1, there is at least 12.1.318 available on the download page)

Edited by eetu

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Ouch that hurts haha

Is anyone aware of how can I work around this issue in houdini 12.1 other than increasing the subsamples? :-)

There was a bug before kinda like this, can't remember which version it was in or when it got fixed though.

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That's a good tip eetu! I'll have the IT guy install it and see if that helps.

Oh yeah, the hip shows you're using 12.1.125 - newer version highly recommended!

(If you're locked to 12.1, there is at least 12.1.318 available on the download page)

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Ah, seems you'd likely need 12.5:

 

Tuesday, August 20, 2013
Houdini 12.5.500: Fixed a long standing bug in the FLIP Solver that caused phantom velocities along the bottom of curved collision containers such as bowls or cups.

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Thank you Eetu,

I'll see if I can filter those out comparing the previous and next frame.

 

Ah, seems you'd likely need 12.5:

 

Tuesday, August 20, 2013
Houdini 12.5.500: Fixed a long standing bug in the FLIP Solver that caused phantom velocities along the bottom of curved collision containers such as bowls or cups.

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