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Sometimes, grid fluid simulations do not have enough splash particles, especially at lower resolutions. With “Yes”, new particles will be created when a splash particle enters the core fluid.
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Secondary bounce
This parameter is interesting for very strong splashes, for example from huge breaking waves, because you can adjust how much the splash particles will bounce against the grid fluid.
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Secondary radius threshold
A particles' radius ranges between 1 (birth) and 0 (death). Secondary splash particles will be created when a particles' radius is greater than the given value.