STL file Import Error

[achodankar]

Hello Developers,
I don’t get an error when I import an STL file created in Freecad. But, I get an error when I import an STL file created in Solidworks. I would really appreciate your help in this matter.

The following is the error:

terminate called after throwing an instance of ‘std::runtime_error’
what(): STL File not valid.
*** Process received signal ***
Signal: Aborted (6)
Signal code: (-6)
[ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x46210)[0x7f9ea3012210]
[ 1] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0xcb)[0x7f9ea301218b]
[ 2] /lib/x86_64-linux-gnu/libc.so.6(abort+0x12b)[0x7f9ea2ff1859]
[ 3] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x9e911)[0x7f9ea33c8911]
[ 4] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0xaa38c)[0x7f9ea33d438c]
[ 5] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0xaa3f7)[0x7f9ea33d43f7]
[ 6] /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0xaa6a9)[0x7f9ea33d46a9]
[ 7] ./cylinder3d(+0x9ebb9)[0x5593a5266bb9]
[ 8] ./cylinder3d(+0x9f377)[0x5593a5267377]
[ 9] ./cylinder3d(+0x219c1)[0x5593a51e99c1]
[10] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0x7f9ea2ff30b3]
[11] ./cylinder3d(+0x21f5e)[0x5593a51e9f5e]
*** End of error message ***
Aborted (core dumped)

Thank you.

Yours sincerely,

Abhijeet C.

[Adrian]

What happens if you open the Solidworks STL in Freecad, save it there and try to open this STL file in OpenLB?

[achodankar]

Hello Adrian,
Thank you very much for your prompt reply. Your suggestion did work out. I can import the stl file successfully in openlb. However, the problem is that the nodes at the wall are not symmetric at all. The top and bottom nodes are not symmetric. It applies the same to the left and right nodes. I have imported a simple cylinder geometry. I would be grateful if you could suggest me how do I solve this issue.

Thank you.

Yours sincerely,

Abhijeet C.

[Adrian]

What exactly do you mean by “not symmetric at all”?

[achodankar]

Hello Adrian,
The arrangement of the nodes on the top, bottom, left and right side is not symmetric. Basically, it should be mirror images(Eg:-circular geometry). That’s not the case presently. I didn’t have that problem, when the geometries were created using indicators.

Thank you.

Yours sincerely,

Abhijeet C.

[Adrian]

Can the asymmetry be explained by a non-center origin of the STL (i.e. it is shifted in some direction?) If so this can be adapted.

Is it still at least roughly following the geometry? (i.e. if you increase the resolution does it converge to the setup you expect?) Maybe a picture and the STL could help me to follow this.

[achodankar]

Hello Adrian,
The asymmetry issue persists even after increasing the resolution. I have ignored the issue temporarily, since for higher resolution it not that much difference. However, from the fundamental point of view, it is incorrect. So, I am pondering if anything can be tweaked in the stl reader.

Here is the link to the image of the geometry: https://ibb.co/zGbNp3s

Thank you.

Yours sincerely,

Abhijeet C.

[mathias]

The voxelizer works correctly. The voxel mesh is slidly shifted to avoid artefacts with nodes beeing exaxtly at an interface which is problematic for offLattice boundary conditions.

[achodankar]

Hello Mathias,
This explanation is very helpful.

Thank you.

Yours sincerely,

Abhijeet C.

[Author]

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