ERROR while simulating Fluid flowing through a rotating geometry
 

Hi,
I am trying to simulate a simple fluid flow through a rotating machinary in FLUENT 2020 R2. Please refer to the geometry in attachemts. The geometry has a sector of a rotating motor with a through hole to accomodate the fluid flow. The fluid flows through that channel and cools the generator.
While simulating, I have used zone motion to fluid and solid geometry. In zone motion, there are two options:
1) Solid motion.
2) Frame motion.

I didn't know which to use and so tried with both the options. While using solid motion, my fluxes are not conserved and while using frame motion, I get a warning like " Significant normal component at one or more faces.." and the simulation basically returns wrong solution.

Could you please help me in solving this error and understanding these concepts

1. While trying to simulate fluid flow in a rotating channel/ geometry, do we have to give zone motion for both solid and fluid (or) only fluid (or) Only solid.
2) What is the difference between zone motion,/ solid motion/ mesh motion/ frame motion.
3) How to deal with 'significant normal component' error?


Thank you for the help.