4 Replies Latest reply on Jul 15, 2013 12:06 PM by Euan Long

    Problems adding lids

    Euan Long
    Euan Long Jul 15, 2013 8:31 AM

      I'm having problems adding lids to this part. I want to add lids on each opening (6 in total, 2 per channel through part), all of which will have boundary conditions (mass flow in to planar face entry, environmental pressure at larger exit holes). The problem is that I cannot add lids to the larger openings as they are not on a planar face.

      Here is what I have tried:

      • For the larger ends I used "create entity" for a 3D sketch then extruded that 0.05 mm to create curved lids.
      • For the openings on the planar face I added lids using the add lids feature - seemed to do it but does not allow me to then apply a temperature condition to the face.

      Any help appreciated as I'm new on here!

      TE.pngTE.pngTE2.png

        • Re: Problems adding lids
          Chris Michalski
          Chris Michalski Jul 15, 2013 8:51 AM (in response to Euan Long)

          What does it say when you try to add boundary conditions to those lids?  My guess is "not lying on the boundary between solid and fluid" which means that your other lids do not completely close off and create a trapped hollow volume for the fluid.

           

          With your  shape I'd likely be inclined to make the lids by using the profile shown in your bottom picture and extruding a thin region all the way across (either inside or outside).

            • Re: Problems adding lids
              Euan Long
              Euan Long Jul 15, 2013 9:42 AM (in response to Chris Michalski)

              Hi Chris,

              That is a great suggestion and it worked to enclose the fluid (see the picture below for the thin feature) - thank you.

              TE.png

              Now I am applying the boundary conditions, but cannot seem to select the inner faces of the fluid boundary. I have tried to make the contours a 3d sketch and choose that profile to apply the condition to but it didn't let me select the sketch (it has to be a surface as I understand). The sketch is highlighted below. I have also got the same problem with the holes on the planar surface - it doesn't let me select the inner circle surfaces to apply the boundary condition to. Any suggestions?

              TE.png

              Thanks for your time, much appreciated

                • Re: Problems adding lids
                  Chris Michalski
                  Chris Michalski Jul 15, 2013 9:55 AM (in response to Euan Long)

                  when you make that bounding surface it needs to re-create the features of your holes.  It looks like you made one continuous solid to close off your fluid volume.  If so, you need to use split lines on those surfaces in order to create the small areas on which to define the boundary conditions.  This will produce the 3 circles and ellipsoids that define the inlet/outlet geometry.

                    • Re: Problems adding lids
                      Euan Long
                      Euan Long Jul 15, 2013 12:06 PM (in response to Chris Michalski)

                      I'd not heard of split lines before, gave it a go and yes it worked thank you. However I later realised that when making the thin extrude that if I merged the thin feature with the component it'd then allow me to later select the smaller inside surfaces for boundary conditions anyway! I'm not sure why I didn't do this in the first place from your advice. Now I have a working model, many thanks for your advice Chris!

                      Euan