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PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 16:52
by zmladen
Hello,
I am trying to learn how to use Elmer by running some of the simulations done by Pavel. I generated the same mesh and the .sif file. The simulation is running but I get strange results (see images). The flux lines in most of the time-steps seem to be ok, but in some time-steps i experience some sudden jumps.
- cogging_torque.png (33.01 KiB) Viewed 1519 times
Cogging Torque
- field_plot.png (235.14 KiB) Viewed 1519 times
Flux density plot
I am runing the simulation on the elmerfem virtual machine with the latest elmerfem 9.0 version installed. Is the setup in the .sif file still up to date?
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 16:59
by raback
Hi
You should give more information on what kind of mortar BC it is: galerkin projector & rotational projector.
-Peter
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 17:01
by zmladen
Hi Peter,
thanks for the fast reply. How to do that?
Thanks,
Mladen
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 17:23
by zmladen
Hi Peter,
i just added "Rotational Projector = Logical True" in the sliding boundary definition and the obtained torque looks much smoother.
Code: Select all
Boundary Condition 2
Target Boundaries(1) = 2
Name = "Sliding"
Discontinuous Boundary = Logical True
Save Line = True
Mortar BC = 3
Rotational Projector = Logical True
End
- cogging_torque_smooth.png (21.86 KiB) Viewed 1511 times
Thanks again for the help!
Mladen
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 17:37
by zmladen
What is the meaning of "Mortar BC = 3"? In this example the mesh consists from only one sliding boundary with the number 2.
Code: Select all
Boundary Condition 2
Target Boundaries(1) = 2
Name = "Sliding"
Discontinuous Boundary = Logical True
Save Line = True
Mortar BC = 3
Rotational Projector = Logical True
End
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 18:14
by kevinarden
A mortar condition is between two boundaries, they are always in pairs, so boundary 2 as defined by the target boundary is mortared to boundary 3 as defined by Mortar BC = 3. The mortar conditions between the two boundaries are specified by the user.
Boundary Condition 2
Target Boundaries(1) = 2
Mortar BC = 3
This is set for the non-mortar (slave) boundary to refer to the boundary condition index of the
corresponding mortar boundary. The mortar boundaries always come in pairs, but the settings
are only given in the context of the non-mortar boundary.
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 18:25
by zmladen
I understand that the Mortar condition needs 2 boundaries. But in this example there is no boundary 3 defined in the sif file. Only 2 boundaries are defined. It seems that the model is made in such a way that boundary 2 is "master" and "slave" boundary in the same time.
Thanks,
Mladen
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 19:18
by kevinarden
Since Boundary 2 is defined as belonging to elements on both sides, and Discontinuous Boundary = Logical True is on, then the code understands that there needs to be a mortar condition to the both sides. Therefore the Mortar BC = 3 does nothing, and can be deleted from the SIF.
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 03 Jan 2022, 19:34
by zmladen
That makes sense, thanks a lot!
Mladen
Re: PMSM Simulation from Pavel in ElmerFEM 9.0
Posted: 04 Jan 2022, 18:03
by zmladen
I made some tests and it looks like "Mortar BC = 3" cannot be deleted from the SIF. However, the number 3 is not relevant. It can be any number other than the numbers used in the defined boundaries. If deleted the solver shows "discont" message and appends "discont_" to the result file name.