Help Fluid oddities at <= 4 particles

[josemendez]

No sticky issues in Obi 7 with 1-4 particles   (but a new visual bug: At 2 particles the fluid mesh is invisible, so I added 2 fake particle sphere meshes)

That's not a bug, reduce your ObiFluidSurfaceMesher's isosurface value to a smaller value. This will allow areas with less density to be captured by the mesh, if your isosurface value is above the density field that a single particle (or 2, or 3, etc) yields, it will be ignored during mesh generation.

Also, you migh want to reduce the solver's max anisotropy value. This will deform particles into ellipsoids that approximate the shape of their local neighborhood, which looks good for large-ish particle formations but won't look that good on just 2 or 3 particles, as it will result in cross or star-like shapes.

In your scene, I found that max anisotropy = 1.5 and isosurface = 0.05 works well.

Back in my Obi 6 project, changing Viscocity from 10 to 1 .... seems not to change much of the jitter or meandering. I think upgrading to Obi 7 is the solution.

Viscosity = 10 is very likely to make the simulation unstable. High viscosity values require a extremely small timestep to be stable, for this reason the manual recommends keeping it below 2.

P.S. Obi 7 is very nice! The reduction in components is great. Seeing the fluid mesh in the editor is incredible!! And there are some nice new callbacks as well.

Thanks!