When DesignModeler is a better choice than SpaceClaim

Rochester Institute of Technology Clean Snowmobile Team is an ANSYS sponsored team using Forte to predict engine emissions. RIT obtained the solid geometry from the engine manufacturer as a SOLIDWORKS (SW) file. I volunteered to help with geometry preparation to extract the fluid domain and partition the surfaces to make it ready for import into Forte. 
Eric Oswald is a fifth year Mechanical Engineering student who is doing the Forte simulations.

Both DesignModeler (DM) and SpaceClaim (SC) can do the Fill operation to create a solid model of the fluid domain, but an important difference was revealed. DesignModeler and SOLIDWORKS both use the Parasolid geometry modeling kernel, while SpaceClaim uses the ACIS kernel. That means moving data from SW to DM is just a write and read operation, while moving data from SW to SC is a write, read and translate operation. Most of the time, this translation between the two kernels has no effect, but sometimes it causes a problem.

Below is the image of the inlet port as seen in DM and it looks the same in SW.

Here is the image of the inlet port as seen in SC. Note the spike defect just right of center.

In this case, I decided to use DesignModer to complete the geometry preparation!


  • vganorevganore Pune, IndiaPosts: 715Admin
    edited January 2018

    Interesting story Peter. Is it difficult to fix the defect in SC or we can't fix it?

  • peteroznewmanpeteroznewman Posts: 13,251Member
    edited January 2018

    Hi Vishal, I tried the repair tools in SC but could not fix the defect. Attached is an ANSYS 18.2 archive of the geometry in DM and SC if anyone wants to try. The defect in the attachment looks different than shown above. Maybe the one above is after attempting a repair.

  • vganorevganore Pune, IndiaPosts: 715Admin
    edited March 2018
  • FernandoTorresFernandoTorres Madrid, SpainPosts: 74Member
    edited May 2018

    Hy Sir peter ! Great explanation.

    But instead of 3d modelling , if we are dealing with 2d i.e. want to import a 2d sketch to mechanical from another software , do we have to use "CONCEPT , SURFACES FROM SKETCHES" each time for large sketches ? For example if I am an AutoCAD fan of 2d modelling , and import a complex 2d sketch into DM , do I have to make surfaces by CONCEPT"SURFACES FROM SKETCHES" every time?

  • peteroznewmanpeteroznewman Posts: 13,251Member
    edited May 2018

    Can AutoCAD create a bounded surface in the 2D drawing environment, or only lines and curves?  If it can create surfaces, then you may be able to import and mesh directly on them. If you can't create surfaces, then you have to make surfaces in DM (or SC).

  • FrankDFrankD Concord, MAPosts: 52Member
    edited June 2018

    Peter and Vishal

    I appreciate the example -- translation is to be avoided if possible. However, I like to think that there is always a way to repair geometry, and strictly following the Repair tools is not always going to be the way to go.  In this case, when you have geometry that is apparently 'all bad' like this, your only recourse is to delete the offending faces and get them in there somehow, again.  You can recreate them, but in this case we got lucky because the intent of the part appears to be symmetry; and the other tube of the manifold looks good.

    I made a temporary plane through the axis of what seemed like the center hole between the inlets (outlets?) and copy-pasted the good surface and mirrored it about the plane.  They looked like a perfect match, to me. Then delete the bad face (there was just one) to turn the whole model to surfaces, as you can see above. The first try didn't choose the right side of these little nubbin surfaces (or perhaps I forgot to select them, see how they appear to float inside, unconnected to anything):

    But a simple undo (to before the deletion,) copy-paste both nubbins (6 total faces,) do the delete again, and select the 4 surfaces to Merge in Combine, and you are done:

    Back to solid part.


  • sma4tsma4t Posts: 13Member
    edited September 2019
    Thanks for the interesting topic. I Thought the SCDM would "always" be the way to go. But it seems that's not always the case.
    I wanted to share this pdf which shows similar cases where each software would be more suitable to use than the other.
  • sma4tsma4t Posts: 13Member
    edited September 2019



    I was wondering if saving the SW file as .stp and then importing into SCDM would solve the issue? This technique is recommended by SC's help and saved me from troubles lots of times. 

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