Liquid (particle sampler) is passing through the collider

I’m experiencing problems setting a liquid (particle sampler isosurface) inside a cup because it pass through the collider when the cup moves. I realized that it also happens in the simulation demo “Hand Pouring Liquid”, available in Create 2022.2 (deleted in 2022.3). In my application and in the demo the cup collider is set to “Convex Decomposition”.

If you move gently the cup, the liquid behaves as expected. It only appears when the acceleration is high enough either moving manually the cup in the viewport or another external objects interact with it. I tried enabling CCD but apparently has no effect.

Is there a way to avoid this error?

I’ve found a possible workaround here and is by setting the max velocity of the particle system, which is by default infinite, to a value close to 1 m/s. In this way the liquid hit slower the collider and doesn’t pass through it.

However, this smaller max velocity also has an effect to the fluid which behaves less realistic as it moves slowly, looking like it has a higher viscosity or lower gravity. Thus, I would like to find an official fix for this problem.


Hi @dgarcialopez - if the liquid spills, it means that some particles are missing contacts that could prevent them from tunneling.

Can you please try increasing the contact offset of the particle system?

The default value is auto-computed from the particle contact offset main parameter according to these formulae to give you a hint at how you can start the tuning:

CCD is not yet supported, even though the checkmark is there. Apologies for the misleading UX here.

Thanks for the reply @philipp.reist! Adjusting the contact offset fix it. For future reference the Particle Contact Offset was set to 0.005 and a value of 0.05 of Contact Offset made the liquid to not to spill.

When CCD will be supported to avoid setting this parameter manually?

We have no timeline yet for support of CCD for particles, as this feature is not a priority currently.

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