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Flouquet periodicity on Eigenfrequency analysis 3D

Posted Aug 16, 2013, 8:38 p.m. EDT RF & Microwave Engineering Version 4.3a, Version 4.3b 2 Replies

Ruth Rubio
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Hi everyone!
I'm trying to obtain dispersion curves for a 2D periodic structure in 3D. Already build the geometry (basically a ball inside a box), assigned the materials, and set the Flouquet periodicity at all boundaries x,y,z. But all I get is:
Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
and then it lists some points in the 3D geometry. But I already checked and they are meshed and have material setup. What could be wrong?
Thanks in advance for your time at reading/replying this.
Ruth
2 Replies Last Post Sep 10, 2013, 10:15 a.m. EDT
Frank McDermott
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Posted: 1 decade ago Aug 30, 2013, 4:59 p.m. EDT
I've done similar simulations and 99% of the time I got errors was when the mesh for each periodic condition boundary isn't the same. (You do have a separate periodic condition for each dimension right?)

To verify this is the cause try disabling the periodic conditions and running your simulation. Enable each one individually until the error reappears to find the problem meshes.

To fix this: mesh one side of each boundary and then use 'Copy Face' to copy the mesh it to it's respective pair.

I've done similar simulations and 99% of the time I got errors was when the mesh for each periodic condition boundary isn't the same. (You do have a separate periodic condition for each dimension right?) To verify this is the cause try disabling the periodic conditions and running your simulation. Enable each one individually until the error reappears to find the problem meshes. To fix this: mesh one side of each boundary and then use 'Copy Face' to copy the mesh it to it's respective pair.
Mexmc
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Posted: 1 decade ago Sep 10, 2013, 10:15 a.m. EDT
Hi Ruth,

Has anyone managed to create a working Comsol file that solves this problem in version 4.3a?
If so, could you please share it?! I'm quite new with Comsol and your help would be gratefully acknowledged. Thanks in advance.

Mike
Hi Ruth, Has anyone managed to create a working Comsol file that solves this problem in version 4.3a? If so, could you please share it?! I'm quite new with Comsol and your help would be gratefully acknowledged. Thanks in advance. Mike

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