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Electromagnetic Periodic Boundary Condition
Posted 9 août 2012, 12:00 UTC−4 Version 4.1 2 Replies
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I am trying to simulate a 2D periodic electromagnetic structure using periodic boundary condition in comsol multiphysics. the whole structure is 3D but it has 2D periodicity in x and y directions.
There are a lot of options in periodic conditions Tab including "Type of periodicity", "Constraint Type".
I can just use one of those options because the rest makes error.
What I am using is "continuity" in "Type of Periodicity" and "Unidirectional" in "Constraint Type".
At the rest options, simulation runs up to some percentage and then it stops and makes error after a while.
Although I can simulate the structure with above mentioned periodic conditions but when I am calculating reflection and absorption of that structure it gives wrong results.
I am calculating reflection and transmission using Poynting theory. So I am calculating the power transmitted through different transmission and reflection planes.
When I am using this method by PEC an PMC boundary conditions, It gives correct results which the results correspond even to calculated results with scattering parameters, but this calculation does not work for periodic BC.
The structure should have resonance at 0.87 THz which it has resonance at the same frequency but the amount of absorption (A=1-R-T) gets higher than 100% or even it changes when I am changing the reflection plane of my calculations.
I am not sure now if my method of using periodic boundary condition is wrong or my calculation is wrong, but I think that I may do wrong periodic boundary conditions.
The surprising thing is that I tried aslo to use exactly same mesh on symmetric boundaries but the results are totally different from what I got with nonsymmetric mesh.
When I want to use periodic BC, I am using two periodic boundary Tabs and I am putting pairs of symmetric boundaries in each of them. I am selecting boundaries in x direction in one of the Tabs and boundaries in y direction in another Tab. I am using scattering BC for z direction boundaries.
I appreciate if someone can help me.
Hello Mohammad Parvinnezhad Hokmabadi
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Dihan Hasan
OR, US
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4.1
Hopefully I solved the problem by myself.