How to fill Room and duct assembly in Fluent
 

Hi,
I am working on project where I need to supply air from duct inlet to Room through duct slots and simulate results.

Here, I prepared draft assembly in solidworks and imported to
Ansys but I don't know how to fill air as a material in assembly like this.

Please consider attached IGS File and image for a reference.

I really appreciate your time and looking forward to all possible solutions.