The computation of certain particle channels is sometimes computationally expensive, although you will hardly recognize any effects in terms of the fluid's dynamics and its behaviour. The true power of these channels is normally only visible during the render process, for example when you use vorticity for shading purposes. You can decide whether you want to include the channels, listed here, or not.
Vorticity
If you want to calculate the grid particles' vorticity, change this option to “Yes”. Vorticity is a computationally intensive process and therefore deactivated by default.
Normal
If you want to add a normal channel to the grid fluid particles, please switch to “Yes”. Here we talk about the surface normal at the associated particle’s position.