Lumpy Water

[josemendez]

Increasing the iterations of the Density constraint seems to help, but I can still get this lumping to occur pretty easily.  The attached pictures are with 12 iterations.

I've also tried playing with the relaxation.  Lower relaxation values seems to help, but comes with the added issue of un-evening the distribution of the particles throughout the fluid volume. 

Relaxation is just a multiplier on constraint "force". Lower relaxation values simply enforce constraints less strictly. Applied to density constraints (whose job is to enforce even distribution of mass over volume and hence, even spatial distribution of particles) will result in uneven distributions.

I still think this is just due to discretization, and the fact that there's very few particles in there. If you set the max anisotropy to the minimum value (1) you'll see the problem more clearly.

On the surfaces of the fluid (surface, walls, and floor), the particles seem compressed (overlapping each other) while a void area (blank space with no particles in it) forms just above the floor surface. 

When max anisotropy is set > 1, particles will be "pulled" towards the surface and flattened into ellipsoidal shapes, to try and get a smoother surface. This will result in less densely packed fluid volumes, since particles try to make a smoother surface.