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.
Vorticity
When enabled the particles' vorticity is calculatedVorticity hardly contributes to a fluid's behaviour and is therefore disabled by default in order to improve performance. But, vorticity is often used for shading effects, the Hybrido mesh's "Vorticity attenuation" or the generation of secondary particles.
You have to activate the channel "Vorticity" here, but also in the "Export" tab's "Particles cache (.rpc)" resource, otherwise the data will not be stored. The same applies to "Particles cache -Alembic- (.abc)" entry. The channel has to be enabled before the core fluid simulation starts!
Normal
When enabled the particles' normals are calculated. Here we talk about the surface normal at the associated particle’s position.
You have to activate the channel "Normal" here, but also in the "Export" tab's "Particles cache (.rpc)" resource, otherwise the data will not be stored. The The same applies to "Particles cache -Alembic- (.abc)" entry. The channel has to be enabled before the core fluid simulation starts!