1 Reply Latest reply on Aug 10, 2011 3:08 PM by dink dinkler

    High Mach Errors in very slow flow model...???

    dink dinkler

      Forgive the pen-name. I created this account long, long ago and can't seem to figure out how to change it.

       

      I am doing some flow analysis for heat loss and flow profiles on a commercially available helical coil tube-in-tube liquid/gas heat exchanger.

      Wow that was a mouthful.

      If you couldnt follow that... just click on this. http://sentry-equip.com/Public/BrochuresandDataShee/DTC17.1.pdf

      I am modeling a "Series 4" but have truncated the model to 4 coils vs. 16.

       

      Well my mass and volumetric flow rates are super small and have been too low for even the vendor to spec out a total length that I need.

      So I am trying to do a part level analysis and will later plan on doing a full system analysis too.

       

      Well, now I am not only having SUPER slow CPU time, but I am getting some high mach errors which is rather curious.

       

      Admittedly the size of the tubing may be oversized for the flow rates (programmatic decisions beyond my control), but I cant imagine that this is the culprit.

      I'm stumped.

       

      Thoughts?

       

       

       

      BoundaryConditions.JPGCoilHEX.JPG

        • Re: High Mach Errors in very slow flow model...???
          dink dinkler

          I think I figured this one out through repeated frustrationand "try, try again" approach.

          It seems the fundamental issue I had here was that I had attempted to make for a "simpler" simulation by complicating the parts.

           

          By that I mean that the coaxial tube setup was created as one single part rather than 2 coils to be placed independantly into an assembly and mated.

           

          Well now it runs just fine.

          Although I am still getting fairly long CPU time I am getting full 100% progress and acheived goals without any of the mach or vortex errors.