How can I make my model "watertight' in order to run Flow Simulation on Solidworks?

I am trying to run a internal flow simulation on a wind tunnel using SolidWorks, however once I add the lids to the entrance and exit, check the geometry, it says the model is still not watertight.

I have attached the wind tunnel to this and any help would be much appreciated.

1 Answer

After examining the assembly my guess is that you have errors in matting the parts together. First delete all the mattes and then leave only the contraction cone part fixed. the apply coincident mates to all the contact surfaces between the parts and only then align them. I created a sketch with a circle on the diffuser part in order to make it concentric with the outer fan end part. I am uploading a new assembly for you and a new diffuser part. Good luck.