1 Reply Latest reply on Feb 7, 2011 11:43 AM by David Harrold

    Selected faces do not belong to fluid subdomain - can not get passed it

    Liz Veres

      Hello.  We do not use flow simulation frequently, but when we do intermittently we run into "One of the selected faces does not belong to the fluid subdomain."  Sometimes we get passed it after multiple tries without really being able to tell what difference got it to work.  On the model we are working on now we have tried both the automatic lids and making our own lids, and can't get passed the problem.  After multiple tries we were able to get it to work on the water side (circular entrance and exit), but we can't get it to work on what will be the flue gas side which is sheet metal at the entrance and exit.  We're making sure we have overlap.  Thanks for any help you can provide.

        • Re: Selected faces do not belong to fluid subdomain - can not get passed it
          David Harrold

          Hi Liz,

          I've run into this problem on several occasions. I sometimes run into this when setting up large assemblies for flow modeling.


          Navigate to the Flow Simulation tab, and click the icon called "Check Geometry." This is also located under Flow Simulation > Tools > Check Geometry. In the dialog that appears, click "Fluid Volume" and you can view the fluid volume of your model. A list of Invalid Contacts is shown in the dialog.  Try toggling "Exclude cavities without flow conditions" to see if this provides further insight, which will depend on your model. You can Disable components systematically to troubleshoot your problem. (Disable is similar to Suppress, but a little faster.)


          Usually for me, the problem is that I have some invalid line contact  somewhere, so I just modify the model a little to satisfy the flow  solver. Or sometime there's a bolt missing, leaving an open hole somewhere, which messes up the fluid volume.


          I've had mixed results with Automatic Lids. You could also try making Automatic Lids at the part level, as opposed to the assembly level. But I think it's faster to create a part configuration with the holes suppressed.


          Hope this helps!

          Dave Harrold