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Iso surface plot with artifical "lines"

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Old   April 26, 2016, 01:19
Default Iso surface plot with artifical "lines"
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I partition my grid in the y and z directions during my CFD run. The tecplot output follows the same partition. However, I found that when I used many procs (1000+), I got my Iso surface plot with artifical "lines" as shown attached.

Do you know what cause them? Or how can I eliminate them?


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Old   April 27, 2016, 14:59
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We here at Tecplot cannot say for certain what is causing this issue. As you probably realize, it could be something to do with some face neighbor weirdness when you stitch the 100+ files back together for visualization.

Would you be able to share the file to us for further examination?

If so, then send me an email to s dot rumage at Tecplot dot com to make the file transfer arrangements.

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Old   May 12, 2016, 16:18
Default Tecplot MPI utility reference
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Thank you for sharing a dataset with us.

We think what we are seeing are interpolation discontinuities between your partition zones. When Tecplot calculates the nodal values from the cell centered source variables it doesn’t take into account cells from neighboring zones unless there are explicit connections via face neighbors (what Tecplot calls global face neighbor connections).

Global face neighbor connections connect the exterior cells between partitioned zones. So, one solution is to provide those connections.

As another alternative, the MPI version of the TecIO library will allow each CFD processor to write its own partition (using MPI TecIO) and then the master node will assemble together the partitions into a single ordered IJK zone (again using the MPI version of TecIO). The MPI TecIO produces SZL formatted data. SZL of course being Tecplot’s newest data format ( szplt ) especially designed for large partitioned data.

For more information & access to MPI TecIO, please visit this page:

Note: If the global face neighbor connections are supplied, Tecplot will only use them if Laplacian averaging is used (Laplacian averaging is selected in the Performance dialog found by selecting the “Options->Performance… menu option, then selecting the “Accurate” option for “Variable Derivation” under the “Misc” tab of the “Performance” dialog). Without global face neighbors this option will not help you.

We hope this information is helpful to you.
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