Fill volume pipe+nozzle simple question
 

Hi,
I received a CAD model (STEP or IGES) of a nozzle connected to a bended pipe and I have to create the fluid domain in order to perform a CFD analysis.

I know that there is the command Fill in Ansys DM to fill the "blank" volumes. My question is:

is there a fast way to select all internal surfaces to fill them or I must select one after another and fill them individually? (which would be a long process)