Okay, this is where I am facing the problem. Using Facesplit in Designmodeler I had separated the domain into two parts the upper part and meshed it separately, where the air is patched later on. Now in fluent when I am trying to set the operating pressure of the upper part to 6000Pa the whole domain is assigned operating pressure of 6000 Pa and not just the upper part. Can you please let me know how to proceed?nThanks.n