Thanks for that. A picture makes things clearer, especially as I'm relying on Google to read Korean!
You need to split a cylinder out around each rotating arm (I assume there are two). Those become the sliding mesh zones. It should be shown in the video, but not necessarily the meshing part: you need to review the sliding mesh options: so once you have three fluid zones (rotors & static zone) do NOT use Share Topology.
Have a look for mixing tanks on here: it's a similar approach in that the mixer units rotate inside a tank.
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