Parametric study using SpaceClaim in prepare for fluent, loss of shared topology

    • Tim Weber

      Hi everybody,

      I want to conduct a parametric study with fluent. I am giving my issue with bullet-points here to make it easier to read.

      • I designed the model with a different software and imported it to workbench
      • The set-up is two coaxial tubes. the smaller is inserted into the bigger. they are touching, thus the outer radius of the smaller tube equals the inner radius of the bigger tube. fluid will flow through this tube system. 
      • Important, the two tubes are seperate object made out of different materials

      These next steps were made with SpaceClaim

      • I extraced the fluid region and performed share topology
      • I defined the parameter that I want to vary, the outer radius of the smaller tube. Hence, when I change this value, the inner radius of the outer tube should also change so both walls are always in contact.

      This is were a series of issues and incoviences occur

      • When the Pull-feature is used to define the parameter and I change the value of such parameter, both tube merge into one tube. I don't want that since they are made out of different materials.
      • When I choose the no-merge option in the Pull-feature then only one wall/radius changes its size, leaving a gap between the tubes or overlapping them.
        • So how can one made the both wall to be in contact at all time? Making them dependent on each other.
      • So I defined the adjacent radius as a parameter too and coupled them in the parameter window in workbench.
      • When I change the value of the parameter in workbench, the geometry fails to update with the error message that a reference point was lost.
      • The consequence being that the shared topolgy is lost and I cannot conduct the following meshing step.

      So how can I change both radii at the same time with the tubes being two different objects (no merging), and the share topolgy still remains?

      Thank you for the help

    • peteroznewman

      I recommend using DesignModeler to create geometry with parameters. Create one parameter for the diameter that is common to the inner and outer tubes. Create a sketch for each tube profile (cross-section). Create a sketch for the path of the tubes. Sweep the profile along the path to create the solids. Do the same for the fluid profile.  To achieve Shared Topology, in the outline where it shows 3 Parts and 3 Bodies, select the three bodies, right click and select Form New Part.

    • Tim Weber

      Thanks for the answer. I considered that as an option but my model is a bit more complicated as the described two tubes (just used it as an example) and thus, I did not want to redesign the whole thin again.

      I used a different software to make the model and named the desired parameters with DS_, but if I use fluent meshing I can never define these parameters as inputs and they don't show up in SpaceClaim either. (It works for mechanical of course).


    • Rob
      Ansys Employee


      If the NS make it into Mechanical, they must be visible in Workbench. Can you then use the third party tool to create the geometry and read each geometry into Fluent Meshing (or Ansys Meshing) for use in Fluent? 


      • Tim Weber

        But for the parameters to be visible in workbench, one has to tick them in mechanical with a P.

        When using fluent meshing, this option is not available, hence I cannot activates those parameters. Same for SpaceClaim, I cannot find a way to activate the parameters there either.

        It would be nice if it was possible directly from workbench. If I make the mesh with fluent (not fluent meshing) then it works because it is the same as mechanical but! then I cannot use the easy-to-use workflow from SpaceClaim (with extrude volume and share topology) and fluent meshing.

        I like this workflow more, with the drawback that I cannot find a way how to easily handle the input-parameter. And, in fluent meshing there I cannot make mesh-parameters either.

    • Rob
      Ansys Employee

      Fluent Meshing workflows are journal scripts, you just see the input level. However, if you set sizing etc for curvature and proximity those values will adjust the cell size based on the input geometry and surface labels. So, no parameters but the size functions mostly cover for that. 

      Ansys (Workbench) Meshing is Mechanical without the solver. 

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