Gridline Horizontal Artifacts - with Advection Fields

[Wasus]

Advanced (fields and vels) advection operates on all fields and velocities as well. This type of advection is excellent for slow moving fluids while highly divergent and fast moving fields might result in artifacts in a form of lines or crosses. Keep in mind that this advection is very good in preserving small scale detail, so vorticity value can be kept really low (around 0.1).

Quote from FumeFX 2.1 help