CoilSolver Crappy potentials for multi-turn circuit case

[jvencels]

@ettaka
The geometry has two simple turns.

oneCoil.sif - we connect only one turn to circuits, another one is modeled as air. This works.
series.sif - we connect both turns in series using circuits and get an error.
CoilSolver_Circuits.zip

These are the difference in cases:
On the left sif where turns connected in series, on the right - only one turn

Further, there are differences in circuit equations - one component and two components. The circuit setup should be ok as we use it all the time.

[jvencels]

Comparison. On the left it runs, on the right it fails.

[ettaka]

I looked around a bit. Didn't find the problem yet, but I cleaned the case up so it will be easier to narrow the problem down:
only_coil_solver.zip

[jvencels]

I tried running the case, getting convergence problem:

     500 0.4154E+10
     501 0.4154E+10
ERROR:: IterSolve: Numerical Error: Too many iterations were needed.
STOP 1

@ettaka Can you reproduce "crappy potentials" error with cleansed case?

[ettaka]

@jvencels yes, I did reproduce it also. I must have uploaded some other try. I will upload another

[ettaka]

This gives me the error you mention:
only_coil_solver.zip

[ettaka]

I see that the coil current is fine, but the coil current e is terrible

Even if I have commented out "Component 2" here, coil solver seems to still compute the same thing for the other coil turn too (I set Coil Start/Coil End at the boundaries)

[ettaka]

What I found now is that if Component 2 is defined (even if Electrode Boundaries is not used) then the Crappy potentials issue emerges.

And if I compute without Components (with Coil Start/End) Then I get weird CoilCurrent e

[ettaka]

OK. Now I found that CoilSolver was activated in air. It is one issue (not sure if it solves the main issue) because now I get better fields in CoilCurrent e

Nope... This is a separate issue.

So the main issue kicks in when the Component 2 is activated (does not matter if Electrode Boundaries is used or not). One has to inspect what the effect of Components is in CoilSolver next.

[jvencels]

In the case I shared before, the coil solver is not solved in the air.
Regarding Component 2, that sounds like the cause of the problem.

[ettaka]

That is the correct way. I'll try to review further today if I have time.

[ettaka]

I had a look now and it seems that if one adds
CYCLE just before line:

elmerfem/fem/src/modules/CoilSolver.F90

Line 361 in 48ade7a

NoCoils = NoCoils + 1

Then the results are as expected. If one adds it after that line, then the problem re-emerges. FYI @raback

FYI @jvencels, Maybe as for a temporary hack, you can try to use that.

[jvencels]

Thanks, @ettaka
I will proceed with further testing.