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Balancing FLIP velocity and substeps

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Im working on a scene where I have some berries falling into milk. The scene is set at slightly larger than real world scale. When the berries fall they are falling at a relatively fast rate. Because of this the dopnet does not have enough substeps to collide the fluid with the mesh (which is a volume collision) and I get a cratering effect like this.

 

I also have the Re-evaluate SOPS to interpolate geometry box checked on. However It does not seem to do anything. The only thing I can do is increase the substeps in the outer dopnet itself, but because of that interpolation, the velocity is less and I do not get as much splashing.

I thought it was a scale issue, so I increased the scale to a 5 metre bowl. It still gives the same issue as pictures below.

 

If anyone has any ideas about this issue please let me know. I've been banging my head on this project for three weeks.

Screenshot from 2021-01-21 15-33-23.png

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also if i bring down the velocity scale the cratering dissapears, but I get almost no splashing.

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Hi,

In my opinion, the best way to deal with this kind of scenarios is to retime (slow down in this case) the colliders, or even all the animated elements in the scene, simulate at a rate that matches your scene at the new retime rate and finally speed up everything at the same rate that matches the initial pre-retime rate; This way you dont need to use so much substeps to compensate. Also you can slow down the time scale on the solver to not use many substeps or even to compensate the slowing down of your scene.

Regarding time scale on the solver, this is very important when you use the surface tension feature of the FLIP solver, this feature has high subtep hungry, so instead of using many substeps to converge correctly, try to reduce the solver's time scale instead. Ofcourse all of this mainly depends on the scene, the fx, etc, that you are trying to solve.

I hope this heps you!

Cheers!

Alejandro

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17 hours ago, Pazuzu said:

Hi,

In my opinion, the best way to deal with this kind of scenarios is to retime (slow down in this case) the colliders, or even all the animated elements in the scene, simulate at a rate that matches your scene at the new retime rate and finally speed up everything at the same rate that matches the initial pre-retime rate; This way you dont need to use so much substeps to compensate. Also you can slow down the time scale on the solver to not use many substeps or even to compensate the slowing down of your scene.

Regarding time scale on the solver, this is very important when you use the surface tension feature of the FLIP solver, this feature has high subtep hungry, so instead of using many substeps to converge correctly, try to reduce the solver's time scale instead. Ofcourse all of this mainly depends on the scene, the fx, etc, that you are trying to solve.

I hope this heps you!

Cheers!

Alejandro

nice that helps! thank you!!

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