FLIP Particle Separation meaning?

[catchyid]

Hi,

I am new to FLIP. As far as I understand it, FLIP is both grid + particle simulation. In the DOP FLIP Object, I could not understand the meaning of "Particle Separation". Below is its definition in the documentation:

"This parameter controls the interaction distance between particles in the created Particle Fluid Object. Decreasing this value will decrease the distance between your particles making it more impressive, but may also slow down your simulation, since it will take longer to simulate. Decreasing particle separation means more particles that weigh less, but add up to the same mass per unit area."

1) Does Particle Separation equal to Grid Spacing? I am guessing so because the bigger I set it, the lower FLIP grids produced (i.e. pressure, surface, vel). 

2) Why does decreasing particle separation mean more particles with less weight? Does Particle Separation control the number of particles?  Actually, I've noticed that with bigger particle separation I get more particles, but I don't know why/how these particles are created? Isn't that particles are spawned only from SOP Fluid Source emitter? Who creates these new particles?

Thanks

 

[Guest tar]

The cool thing to do is just dive into the HDA to answer the questions:

1) yes there is an expression linking all these i.e. 'ch("../surface_data/divsize") and surface_data is linked with 'ch("../divsize")'

2) how did you set this up to get a SOP Fluid Source emitter? The FLIP fluid from Object only creates a flipfluidobject that uses deeply buried a pointsfromvolume node to generate particles.

[catchyid]

Thanks Marty...As per my second question, I think my description was not clear, basically I've used out of the box shelf-tool "Particle Fluids--> Emit Particle Fluid", so it's the standard network the tool builds (i.e. I've just created a sphere and hit on the shelf tool). However, I could not reproduce the behavior I've described earlier, i.e. a smaller particle separation produces more particles indeed (and not as I suggested before!)...Once more, thanks for your feedback