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Ivar Kjelberg please help! About the shape of PML in comsol 4.4

Posted Jun 24, 2014, 3:56 a.m. EDT RF & Microwave Engineering, Wave Optics, Geometry, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.4 6 Replies

Meng
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Dear Ivar Kjelberg,
I have a question in my simulation. I use the RF module, I was calculating the effective index of the photonic crystal fiber. The shape of the cross section is a hexagonal, the outside is a circle. I want to set the region between the hexagonal and the circle as a PML, and I chose the cylindrical coordinate. But every time comsol said:"Could not find any spherical or cylindrical regions". When I set Cartesian coordinate, the error appear again.

So my question is: does it mean that the pml must be a standard rectangle, circle or concentric? (But in comsol v4.2. the pml region can be arbitrary, it don't have this problem.)

I will appreciate it very much for your helps!
6 Replies Last Post Dec 19, 2014, 9:24 p.m. EST
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Hello Meng

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Zhagsalag Akhyn
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Posted: 1 decade ago Oct 8, 2014, 5:03 a.m. EDT
I have the same problem. Does anybody know how to solve it?
I have the same problem. Does anybody know how to solve it?
Meng
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Posted: 1 decade ago Oct 13, 2014, 5:48 a.m. EDT
I solved it myself, do not set an arbitrary shape of PML, just use circular or rectangular. By careful mesh, the results will be good!
I solved it myself, do not set an arbitrary shape of PML, just use circular or rectangular. By careful mesh, the results will be good!
Zhagsalag Akhyn
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Posted: 1 decade ago Oct 14, 2014, 11:48 a.m. EDT

I solved it myself, do not set an arbitrary shape of PML, just use circular or rectangular. By careful mesh, the results will be good!

Have you solved for 3D spherical or rectangular PML? when i tried i get some other kind of error.
[QUOTE] I solved it myself, do not set an arbitrary shape of PML, just use circular or rectangular. By careful mesh, the results will be good! [/QUOTE] Have you solved for 3D spherical or rectangular PML? when i tried i get some other kind of error.
Meng
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Posted: 1 decade ago Oct 21, 2014, 2:27 a.m. EDT
3D spherical maybe easier, you can refer to the example model of comsol(for example, dipole antenna ), do not forget to use swept mesh!
I hope this help.
3D spherical maybe easier, you can refer to the example model of comsol(for example, dipole antenna ), do not forget to use swept mesh! I hope this help.
Zeba Naqvi
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Posted: 10 years ago Dec 19, 2014, 4:50 p.m. EST
Hello,
I am new to Comsol. I tried to make a simple 2D axisymmetric model with a core circular region 5um in radius of refractive index 1.7 and 0.5 um thick outer circular region of refractive index 1.6. Then added PML at radius 20um and meshed. I selected geometry cylindrical. When I compute, the error is "could not fund any cartesian regions - Feature : perfectly matched layer"
What should I do? Thanks
Hello, I am new to Comsol. I tried to make a simple 2D axisymmetric model with a core circular region 5um in radius of refractive index 1.7 and 0.5 um thick outer circular region of refractive index 1.6. Then added PML at radius 20um and meshed. I selected geometry cylindrical. When I compute, the error is "could not fund any cartesian regions - Feature : perfectly matched layer" What should I do? Thanks
Meng
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Posted: 10 years ago Dec 19, 2014, 9:24 p.m. EST
When the geometry is set to be cylindrical, the problem should have been solved. Moreover, your PML is too thick, one or two lmd is ok!
When the geometry is set to be cylindrical, the problem should have been solved. Moreover, your PML is too thick, one or two lmd is ok!

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