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Hello!

Please look carefully for the names of values: in my case the correct name is ec.JX, ecJY, ec.JZ with capital letters.
If you activate equation view, you can find the names for all values.

Ralf

Hi,

Can you attach the model for better understanding?

Thanks!

Jerry

Hi,

Sorry for responding so late. As can be seen in mf, ec.Jx, ec.Jy and ec.Jz were used for the external current density. I did this because I wanted to input electric potentials in the model and I thought the resulting current needed to be linked to mf using external current density.

As far as I know, the directions of the arrows seem to be as expected. The current induced on the metal sheet is directed opposite to the current in the coil. The shape of the Arrow Volume of the magnetic field caused by the coil also seems to be as expected. Up to this point, the letters of ec.Jx, ec.Jy and ec.Jz in the external current density were black.

However, I added Solid Mechanics afterwards to the model. The letters in the external current density immediately turned orange. Even when the Solid Mechanics Module is disabled, those letters remain orange. Therefore, any subsequent attempts at running the model will fail, even when the last module is disabled. Deleting the extra module returns the orange letters to black.

So, can anyone explain to me why the mere existence of Solid Mechanics has this effect on the external current density in mf? Other modules (such as Beam or even something unrelated as Laminar Flow) do not seem to have this effect. Am I missing some kind of coupling? I am not yet very familiar with COMSOL.


Thanks in advance.

P.S. I had to clear the solutions to make the file small enough for the attachment. Therefore, I made a screenshot of the arrows showing the J and H from mf.

Hi

Pls note the difference between orange and red:
- orange is unit issues it's a warning,
- red is typing error hence failure to run,
while orange will run and give results, that might be correct too ;)

But if it happened when you added a new physics, it gives me the impression that you had hit a COMSOL internal name, and that the new physics has changed the units of your already defined variable, hence unit error, BUT then certainly also solver failure as you are mixing into a same variable 2 distinct physical meanings. This is only a guess, but it's my first idea when I read your issue (I do not have COMSOL accessible just now so I cannot look at the files)

--
Good luck
Ivar

Hi!

In 3.5 there was a similar effect: variable names changes from small letters to capital letters.
If you change from ec.Jx to ec.JX, it will work.
Another problem is, that according to support this coupling of EC and MF includes not the complete equation; there is eps0*epsr*Att missing for transient case...
That's why the calculated EM-forces may be wrong for your solid deformation.

Ralf

...wrong second image...