incorrect magnetic force in 2D axisymmetric magnetic model

Numerical methods and mathematical models of Elmer
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Yeonho Jeong
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incorrect magnetic force in 2D axisymmetric magnetic model

Post by Yeonho Jeong » 01 May 2018, 03:13

I'm a beginner in Elmer.
So far, I have tested many cases on the magnetic analysis using Elmer.
But, I failed to get the magnetic forces in 2D Axisymmetric model.

As a example, I have tried it using a double C-core model with a coil.
Model.png
Model.png (24.35 KiB) Viewed 1876 times
In the results, I got force(1,2,3) = 6.562606332450E+001 1.881623416445E+003 0.000000000000E+000.
Results of FEMM(another 2D FEM solver) are 0 67.3566 0.

I attach the sif and mesh file.
Please inform me on what is wrong.
GapCoreAxi.zip
AnalysisFile
(126 KiB) Downloaded 148 times

Yeonho Jeong
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Re: incorrect magnetic force in 2D axisymmetric magnetic model

Post by Yeonho Jeong » 01 May 2018, 04:19

Also, the distributed patterns of Vector potential line are different in FEMM and Elmer(using Paraview) as followings.

[Elmer <Paraview>]
Fluxline_ElmerFEM.png
Fluxline_ElmerFEM.png (433.03 KiB) Viewed 1876 times
[FEMM]
Fluxline_FEMM.png
Fluxline_FEMM.png (246.51 KiB) Viewed 1876 times


Why different ????

mzenker
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Location: Germany

Re: incorrect magnetic force in 2D axisymmetric magnetic model

Post by mzenker » 02 May 2018, 11:08

Hi,

it seems like one of the solvers makes a mistake here, or both have not been fed with the same input parameters.
If I were you, I would sit back and try to find out what would be the expected physical result. I don't see it right away, and I don't have the time right now to think about it and look into my electromagnetics textbook... ;)
Maybe you could build a simpler geometry where the result can be calculated analytically?

HTH,

Matthias

pavel
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Re: incorrect magnetic force in 2D axisymmetric magnetic model

Post by pavel » 03 May 2018, 19:18

Hi,

have you tried increasing
Steady State Max Iterations?

BR, Pavel

Takala
Posts: 183
Joined: 23 Aug 2009, 23:59

Re: incorrect magnetic force in 2D axisymmetric magnetic model

Post by Takala » 16 May 2018, 13:44

Yeonho Jeong wrote:Also, the distributed patterns of Vector potential line are different in FEMM and Elmer(using Paraview) as followings.

Why different ????
Note that in case you have an axisymmetric case, in Paraview, you need to multiply the vector potential with 2 * pi * r if you wish to plot the magnetic field lines.

So you should take the contour plot from a new variable "a_cont = 2 * pi * coordsX* a" (this you can compute with the Calculator in Paraview). Look at the attached countour plot.
contours_axi.png
Magnetic field lines
(248.8 KiB) Not downloaded yet

Yeonho Jeong
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Re: incorrect magnetic force in 2D axisymmetric magnetic model

Post by Yeonho Jeong » 13 Jun 2018, 03:00

Thank you, Takala !
It works fine in plotting the magnetic field line.

And, I didn't still solve the incorrect magnetic force problem in 2D axisymmetric analysis,
on why the r-component of magnetic force have a big value.

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