I have a piping system modeled in SolidWorks consisting of a reservoir, piping, cavity and volute, and seperately an impeller, like so: http://imgur.com/a/yueDO

The cavity and volute are solids, the piping is a Thin Sweep.  I need to create a volume for the liquid for a fluid simulation in Ansys Fluent, specifically the piping and the reservoir.

The water level is halfway between the bottom of the return pipe and the top of the reservoir.

I'm attempting to use the Core feature in Mold tools, but I'm having difficulty with creating a new part.