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user21
user21
05:21
Go ahead and invite Alex. I think another person to invite is xzczd who actually came up with the UnitStep -> appro idea.
I would be important to establish which equations we want to solve.
I am living and working in Germany; I work for Wolfram Research and I am the developer of the FEM in Mathematica.
 
3 hours later…
Tschibi
Tschibi
08:36
No way :-), I am from germany too ... I did not know, that you can work for Wolfram Research from Germany
At least now I understand, why you know the undocumented Features that well :-)
 
2 hours later…
Tschibi
Tschibi
10:21
Do you have any Idea how I can invite them? The only way I see at the moment is posting the link in one of there answers ...
 
2 hours later…
user21
user21
12:09
@Tschibi, I suppose you have to ping them under an answer with a @ and give them this link. I don't know if there are other ways to do it
 
2 hours later…
Tschibi
Tschibi
14:37
I contacted both of them. Lets see if they answer. Today I could not work on this topic. But I will continue the next days. As I am not as deep within the internal algorithms as a developer I don't know if my approaches will be from high value. If you have any suggestions how I should continue, feel free to tell me. Is it worth trying to access NDSolve via Debuger of Wolfram Workbench?
As I see, Alex followed our invitation. Welcome and thank you very much for joining :-)
Alex Trounev
Alex Trounev
15:04
@Tschibi Nice solution (+1). What question we discussed here? I am not from Germany, but spent my best years in Berlin, Dusseldorf, Wiesbaden, Frankfurt, Munich and Munster.
Tschibi
Tschibi
Nice to know :-) So I guess we will continue this discussion in english. We try to figure out 2 Problems:

Problem number 1. Is the chosen DEQ suitable for that type of Problems, or does it have any drawbacks that we are not aware of. We saw, that for example Comsol multiphysics chooses another Deq https://www.comsol.com/model/download/891901/models.acdc.permanent_magnet.pdf My course about theoretical Electrodynamics was some time ago, and I am not an expert in that field

Second problem is the way, The vector field of magnetization is handled by Curl[]. While it is formally correct that t…
Alex Trounev
Alex Trounev
15:26
@Tschibi Yes, in a case of permanent magnet we use scalar potential, and vector potential we use in a case of current distributed like in my answer on physics.stackexchange.com/questions/513834/…
Tschibi
Tschibi
15:57
How would you define the problem with the scalar potential? How do we bring the direction of the magnetization information into a scalar form?
xzczd
xzczd
16:26
Actually I tried to look into the problem but was somewhat lost. Many materials (e.g. most FDTD tutorial I found) simply doesn't discuss the curl-curl issue, as the issue doesn't exist. There does exist paper discussing the topic e.g. this one: sciencedirect.com/science/article/pii/S0021999196900820 but the content is a bit over my head.
as the issue doesn't exist -> as if the issue doesn't exist
Alex Trounev
Alex Trounev
@Tschibi We can use NeumanValue, for example $-\vec {n}.\nabla V=\vec {M}$. Also, in equation there is $\nabla .\vec {M}$.
Tschibi
Tschibi
16:52
Hello xzczd and thank you also for joining. @AlexTrounev I will try to implement this. It would be interesting if this solution will be more efficient/accurate or not

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