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What's the axial boundary condition?

Posted 22 sept. 2015, 09:13 UTC−4 RF & Microwave Engineering, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5.0 4 Replies

Pu
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Dear all,

I've been using 2D axisymmetric Electromagnetic module. On the axis there's the default axial boundary condition. It's very convenient to use, but there's no way to know what conditions it actually enforces behind (not only for the lowest order m = 0; also for e.g., m = 1). Now I would like to couple it with another model. It's a good attempt to specify a similar axial boundary condition in the new model. Then comes this question...

Thanks for any input!
--
Pu, ZHANG
DTU Fotonik
4 Replies Last Post 13 août 2017, 21:11 UTC−4
Pu
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Posted: 9 years ago 23 sept. 2015, 09:00 UTC−4
By the way, I observe not very smooth solution from EM module with m=1 in 2D axisymmetry. The simulation is just scattering from a sphere. So I doubt the default axial boundary condition might be a cause of problem. I intend to play with boundary conditions on the axis, however it seems it's not possible to add any condition on the axis.

Is there any workaround to specify boundary condition on the axis?

--
Pu, ZHANG
DTU Fotonik
By the way, I observe not very smooth solution from EM module with m=1 in 2D axisymmetry. The simulation is just scattering from a sphere. So I doubt the default axial boundary condition might be a cause of problem. I intend to play with boundary conditions on the axis, however it seems it's not possible to add any condition on the axis. Is there any workaround to specify boundary condition on the axis? -- Pu, ZHANG DTU Fotonik
Pu
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Posted: 9 years ago 28 sept. 2015, 04:10 UTC−4
By checking the Equation View of axial condition, everything is empty there. Does this mean actually no constraint exists on the axis?

Thanks!
--
Pu, ZHANG
DTU Fotonik
By checking the Equation View of axial condition, everything is empty there. Does this mean actually no constraint exists on the axis? Thanks! -- Pu, ZHANG DTU Fotonik
Pu
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Posted: 9 years ago 28 sept. 2015, 09:17 UTC−4
OK... I get something from the reference manual:

In axisymmetric components, boundaries on the symmetry axis are boundaries where only a condition for the axial symmetry exists. COMSOL adds a default Axial Symmetry node that is active on all boundaries on the symmetry axis. The condition on the symmetry axis is typically a zero Neumann or no-flux condition.

But what does it mean by "typically"? There's no way to know if an axis condition is typical or not.

Any guy working for COMSOL give a hint? Thanks!


By checking the Equation View of axial condition, everything is empty there. Does this mean actually no constraint exists on the axis?

Thanks!
--
Pu, ZHANG
DTU Fotonik





--
Pu, ZHANG
DTU Fotonik
OK... I get something from the reference manual: In axisymmetric components, boundaries on the symmetry axis are boundaries where only a condition for the axial symmetry exists. COMSOL adds a default Axial Symmetry node that is active on all boundaries on the symmetry axis. The condition on the symmetry axis is typically a zero Neumann or no-flux condition. But what does it mean by "typically"? There's no way to know if an axis condition is typical or not. Any guy working for COMSOL give a hint? Thanks! [QUOTE] By checking the Equation View of axial condition, everything is empty there. Does this mean actually no constraint exists on the axis? Thanks! -- Pu, ZHANG DTU Fotonik [/QUOTE] -- Pu, ZHANG DTU Fotonik
Pu
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Posted: 7 years ago 13 août 2017, 21:11 UTC−4
This boundary condition should be different for different azimuthal orders. Default axis symmetry boundary condition is no good for all cases.


OK... I get something from the reference manual:

In axisymmetric components, boundaries on the symmetry axis are boundaries where only a condition for the axial symmetry exists. COMSOL adds a default Axial Symmetry node that is active on all boundaries on the symmetry axis. The condition on the symmetry axis is typically a zero Neumann or no-flux condition.

But what does it mean by "typically"? There's no way to know if an axis condition is typical or not.

Any guy working for COMSOL give a hint? Thanks!


By checking the Equation View of axial condition, everything is empty there. Does this mean actually no constraint exists on the axis?

Thanks!
--
Pu, ZHANG
DTU Fotonik





--
Pu, ZHANG
DTU Fotonik





--
Pu, ZHANG
DTU Fotonik
This boundary condition should be different for different azimuthal orders. Default axis symmetry boundary condition is no good for all cases. [QUOTE] OK... I get something from the reference manual: In axisymmetric components, boundaries on the symmetry axis are boundaries where only a condition for the axial symmetry exists. COMSOL adds a default Axial Symmetry node that is active on all boundaries on the symmetry axis. The condition on the symmetry axis is typically a zero Neumann or no-flux condition. But what does it mean by "typically"? There's no way to know if an axis condition is typical or not. Any guy working for COMSOL give a hint? Thanks! [QUOTE] By checking the Equation View of axial condition, everything is empty there. Does this mean actually no constraint exists on the axis? Thanks! -- Pu, ZHANG DTU Fotonik [/QUOTE] -- Pu, ZHANG DTU Fotonik [/QUOTE] -- Pu, ZHANG DTU Fotonik

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