'conductivity is not vanishing (conductivity cannot be considered)'

[jseo977]

Hello! I seem to be getting an error and can't find other posts that had the same error. Could somebody help me out? I am trying to model magnetic stimulation of a nerve with a ferrous core using the Magneto Static Vector Potential solver, but I get this 'conductivity is not vanishing' error.
Could anybody enlighten me as to how this could be solved?
I have pasted the error message below.
Thank you!

Grid size is 159x128x286

Solid settings: frequency = 15000 Hz, characteristic length (worst case domain diagonal) 0.207846
Epsilon Mu SigmaE QS Approx. Quality Static Magn. Field SigmaE/w*Epsilon Solid name
1 1 0 4.2696e-09 0 0 'Background'
1 1 0 4.2696e-09 0 0 'Air'
4.01e+07 1 0.348 0.17108 0.0017803 0.010406 'Nerve'
ERROR: In cells with 'Nerve' the conductivity is not vanishing (conductivity cannot be considered).

Extracting vector potential
Elapsed time for 'Extracting vector potential' was 00:00:00 wall clock time.

ERROR: Simulation 'LF 2' reports an unspecified fatal error! The solver may have run out of RAM.

ERROR: Simulation 'LF 2' failed on 2024-Oct-30 16:07:21
[2024-Oct-30 16:07:21] Released license feature 'QS_SOLVER'.
Peak CPU memory usage: 91.5 MB (95936512 Bytes)

ERROR: iSolve framework failed (see previous error messages).

[Sylvain]

Hi,
There is most likely an error due to a sanity check, since you appear to have lossy tissues in your simulation and the Magneto Static Vector Potential solver does not account for those losses. Having a ferrous core, however, you do need to use that solver.
The trick is to chain 2 simulations: one that solves the magnetic vector potential (A), and one that uses this A as a source term to determine the induced electric field (this time accounting for losses). The key is to remove the lossy tissues from the first simulation (only metallic or ferrous materials play a role anyhow).
I would recommend you have a look at the LF tutorial called "Wireless Power Transfer: Exposure Assessment", since it uses the same technique.

In addition, it seems that "The solver may have run out of RAM"... I would therefore check the RAM usage to make sure it's not going beyond your resources. Note that using the technique above allows you to have two different resolutions: one optimized to properly resolve the coil, the other to resolve the tissues (as long as the domain sizes of the first simulation is large enough to include that of the second). This usually leads to smaller grid sizes, thereby reducing the RAM usage...