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Exodusii mesh size limit to export in ICEM

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    • ethanJ
      Subscriber

      Dear all,

      Our team have been trying to export a large mesh by ICEM CFD. The mesh is purely tetrahedral, with about 400 million cells. There is no problem to generate the mesh, but when I tried to export it into an Exodusii file (because our in-house codes rely on this format), I finally got an error after a long time waiting. I am using ICEM 2021 R1, the first few lines of the error message are attached as follows, the rest are similar except for the specific variables names.

      Error: 

      Running ICEMCFD - Exodus Interface Vers. 21.1.0

      EXODUS II file (double precision) created ... done.

      Exodus Library Warning/Error: [ex_put_block_params]

      Error: failed to complete element block definition in file id 65536

      NetCDF: One or more variable sizes violate format constraints

      Exodus Library Warning/Error: [ex_id_lkup]

      Error: failed to get eb_prop1 array from file id 65536

      NetCDF: Operation not allowed in define mode

      Exodus Library Warning/Error: [ex_put_name]

      Error: failed to store element block name in file id 65536

      NetCDF: Operation not allowed in define mode

      Exodus Library Warning/Error: [ex_put_prop_names]

      Error: failed to place file id 65536 into define mode

      NetCDF: Operation not allowed in define mode

      Exodus Library Warning/Error: [ex_put_prop_array]

      Error: failed to place file id 65536 into define mode

      NetCDF: Operation not allowed in define mode

      ......


      It looks to us that a so-called "element block" structure from the NetCDF library exceeded the size limit (65536) during the internal format transformation, because the mesh size is too large. Does anybody know the library version of the NetCDF and Exodus that are embbed in ICEM 2021? And is it possible to export a very large tetrahedral mesh (such as this one with 400 million cells) into Exodus? Further, could anyone clarify which factors would impact the "element block" size, is it merely determined by the mesh size, does the mesh geometry also do? We'd be very appreciated if anyone can help.

      Best regards,

      YJ

    • Keyur Kanade
      Ansys Employee
      Are you using student version?
    • ethanJ
      Subscriber
      Hi, sorry for the late reply. We are using the standard version.
    • Keyur Kanade
      Ansys Employee
      Can you first please try a small case like 500K or 1M cells and check if export works.
    • ethanJ
      Subscriber
      Yes, there is no problem to export small meshes. In fact, the largest mesh we've ever successfully exported is with about 100M cells. But it looks like there is a limit that stop exporting an even larger one.
    • Keyur Kanade
      Ansys Employee
      I have never used this export. May be RAM limitation?
      Can you please check if you can export 200M or 300M ?
      Regards Keyur
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    • ethanJ
      Subscriber
      We tried a 200M case on a machine with 1T memory, but it also failed to export. The memory should not be the problem. The error information (as shown in the first post) suggests it relates to some internal limits of the NetCDF and Exodusii library, which are invoked by ICEM during the exporting. Do you, by any chance, know any details on these two libraries that are embedded in the latest Ansys (2021, R1)? Such as their version numbers. Thank you very much.
      YJ
    • Keyur Kanade
      Ansys Employee
      In help there no limitation mentioned.
      Select Solver (ansys.com)
      Can you please cross check mesh quality. If quality is poor, it may give errors.
      Regards Keyur
      How to access Ansys Online Help Document
      How to show full resolution image
      Guidelines on the Student Community
      How to use Google to search within Ansys Student Community
    • ethanJ
      Subscriber
      Will do. Thank you.
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