nI noticed your file had extra surfaces that defined outlets from the room. Did you delete all of those extra surfaces? You don't need them because there are faces on the room body where those surfaces used to be.nDid you use the Share button on the Wokrbench tab in SpaceClaim?nIn Meshing, did you see any contacts created under the Connections folder? Delete them.nLooking at your model, the element size is too large. Set the Element Size to a smaller number, don't leave it as Default. That should fix the meshing issues. nI don't understand how you extruded the round diffusers. Did you do that on both the Duct solids AND the Room Body? In one case adding material and in another case removing? This should not be necessary to get a good mesh.nIt's okay to have a wall and a shadow-wall because you have fluids on both sides of that wall. This allows Fluent to define a property of the wall for the air inside the duct separate from a property of the wall for air in the room.n