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17.3 Pointwise can NOT import CGNS mesh with Multiple nodes

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Old   January 21, 2017, 13:09
Default 17.3 Pointwise can NOT import CGNS mesh with Multiple nodes
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swm
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Hi guys,

I've encountered a strange problem which keeps puzzling me for a week
I exported a mesh with CGNS format in Numeca Autogrid and then imported it with Pointwise, but it failed!

The error message is clear: 'File contains multiple base nodes'. I also looked it up in the User manual which told me pointwise could only load CGNS mesh with single base node.

But this kind of mesh can be imported successfully with ICEM or CFX-Pre. To my surprise, the widely-accepted mesh generator Pointwise can not even support it! I'm wondering whether I set something correct or just need to modify some parameters to make pointwise work well with such kind of CGNS mesh.

Does anybody have some suggestion or solution? (Although I can export the mesh in Autogrid with Plot3D format, it loses all the BC info which is critical to show the connection between multiple blocks. So that I have to export it with CGNS format)

Many thanks.

error.jpg
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Old   January 23, 2017, 11:28
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David Garlisch
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You have encountered a known limitation in Pointwise's CGNS import. We already have a feature request in our system to address this situation.

However, for now, there is no workaround other than to split the single file into multiple files with a single base node per file.

Multi node files are usually used to store time stepped grid and solutions. In general, each base node is supposed to represent a self-contained grid database. So when multiple nodes are present, which node should we load?

Looking at the CGNS docs, it becomes clear that there is much variability in multi-basenode files. This variability is application dependent.

Quote:
6.2 CGNS Entry Level Structure Definition: CGNSBase_t

The highest level structure in a CGNS database is CGNSBase_t. This top level entity is designed to be self-contained, a complete CFD computation can be archived and reproduced using the data defined in the CGNSBase. However a CGNS tree can contain more than one base, these can be related to the same CFD case or not. The behavior of a multi-base CGNS tree is application dependant...
While Pointwise has room for improvement here, it is not a trivial problem to handle in general. Different vendors can produce wildly different CGNS files that would be difficult to support.

If you are willing to post a multi-basenode CGNS file, we can take a look at it and attach it to the feature request and use it for reference when adding this feature.
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Old   January 24, 2017, 09:32
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Hi David,

Thanks for your explanation. May I ask how to 'split the single file into multiple files with a single base node per file'? Just delete other nodes but keep one node each time?
1.jpg

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Old   January 24, 2017, 10:48
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Quote:
Originally Posted by swm View Post
Hi David,

Thanks for your explanation. May I ask how to 'split the single file into multiple files with a single base node per file'? Just delete other nodes but keep one node each time?
Attachment 53486

swm
Looks like you are using CGNSview. Yes, delete the other nodes and save as a single node file.
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