Creating Fluid Body Inside Solid Part
 

I the stp files from a ProE drawing of an exhaust stack. I am using ANSYS Workbench 13 with CFD FLUENT. I want to take the solid stack walls that I've imported, and create a fluid body inside. Does anyone have experience with importing solid bodies for a CFD simulation?

Use the fill option in design modeler, I think its under tools > fill. then pick the inner surfaces and it will fill, you may have to specify "add frozen" instead of "add material"