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Issues with meshing domain with many lines

Posted Feb 17, 2020, 7:50 a.m. EST Geometry, Mesh Version 5.5 1 Reply

Daniel Fredriksson
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I'm trying to solve a problem where the domain is a unit cube with lines generated via a periodic voronoi tesselation. I require these lines for my physics. I am very often running into issues when I try to mesh this domain. Some tesselations succeed and some do not. Often the error is either "failed to insert point", "intersecting edges" or similar. Sometimes when the mesh does succeed the solution will fail due to inf and NaN in the stiffness matrix. Since this solution error only appears some times I'm assuming it is also caused by the mesh.

How should I buid my mesh procedure to effectively mesh my domain? I've tried meshing along the edges and boundaries first but this does not help any. I've tried collapsing the short edges and removing details but these do not improve the success rate either.

I have attached an example of what the tesselation may look like. Due to the sometimes very tight intersections between lines I do not expect every tesselation to be possible, but currently I have around a 10% success rate which I too low.

1 Reply Last Post Feb 18, 2020, 2:00 a.m. EST
Bjorn Bretz COMSOL Employee

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Posted: 4 years ago Feb 18, 2020, 2:00 a.m. EST
Updated: 4 years ago Feb 18, 2020, 2:41 a.m. EST

Hi Daniel,

In general, it is recommended that you mesh the entire geometry with one operation if possible. For this model this means that you should only use one Free Tetrahedral node, perhaps with Size nodes defining appropriate sizing on the lines inside the domain, instead of first using Edge and/or Free Triangular nodes, creating mesh on edges and faces, followed by a Free Tetrahedral node to mesh the interior (domain). The motivation for only using one operation can be found in the following blog.

https://www.comsol.com/blogs/best-practices-for-meshing-domains-with-different-size-settings/

If you need further assistance I suggest you contact COMSOL support.

https://www.comsol.com/support

Regards,
Bjorn Bretz
COMSOL Development

Hi Daniel, In general, it is recommended that you mesh the entire geometry with one operation if possible. For this model this means that you should only use one Free Tetrahedral node, perhaps with Size nodes defining appropriate sizing on the lines inside the domain, instead of first using Edge and/or Free Triangular nodes, creating mesh on edges and faces, followed by a Free Tetrahedral node to mesh the interior (domain). The motivation for only using one operation can be found in the following blog. https://www.comsol.com/blogs/best-practices-for-meshing-domains-with-different-size-settings/ If you need further assistance I suggest you contact COMSOL support. https://www.comsol.com/support Regards, Bjorn Bretz COMSOL Development

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