Meshing a Pumping Circuit
 

I've modeled a circuit consisting of a open reservoir, a volute, cavity, and piping in SolidWorks, as well as an impeller. The reservoir consists of a large rectangular section, with a baffle in the middle. Images for clarity. The volute and cavity are solid, the piping and reservoir are thin sections. I've imported the models into workbench as Geometry (one for the impeller, one for the circuit), now I'm trying to mesh them for a Fluent simulation.

I've never used Ansys Meshing beforehand, and I wanted to ask beforehand, as I'm unsure about free surfaces. I've watched this tutorial http://www.youtube.com/watch?v=RELLrEJ9chg#t=582s , and I want to use the methods they describe there. The video mentions cutting the model into meshable sections, and specifying Sweep Method and Inflation steps to control how the volume is meshed.

My question is, how do I create a mesh for the liquid volume in the circuit? My guess is to first create two faces on the top of the reservoir to "cap" it (and set those two faces as a free surface when meshing - the average liquid level won't change and is halfway between the bottom of the return pipe and the top of the reservoir?), create a volume, then use the above methods to break the volume?

I'm guessing I will need two domains for the simulation, a "dome" shape for the impeller, and another shape that meets up with the dome for the rest of the circuit, that way there is just one surface in the interface.

You can probably tell by my mixed language that I'm very new to this, so any help or directions are greatly appreciated.