FLUX3D - magnet segmentation

Dear all,

I am trying to simulate a segmented magnet in Flux3D. To this extent, I have divided the magnet into two volumes, and assigned a (different) volume region to each of the volumes. The properties of both volume regions are the same (solid conductor region with magnet material; linear Br and relative permeability; linear resistivity). Further, I defined a face region at the face that interconnect the two magnets, in order to impose an insulating layer. I have tried different settings for this face region (air gap region, magnetic non-conducting region with mu_r of 1, perfect insulator in conduction medium), but in all cases I get an error message:

"The coupling with neighbouring volume regions of faces:
27
of face region REGIONFACE_1 is forbidden."

for airgap and magnetic non-conducting region and:

"The electric insulator surface region REGIONFACE_1 , on faces:
is not edge of volume regions with M*3TWSCRHJ or M*3TWOM
formulations"

for perfect insulator region. I have tried the same approach in Flux2D (with air gap region), where it worked perfectly. Can you explain why I am getting this error message in Flux3D? Is there another method to include the insulation layer between the magnet segments without modeling it as an actual volume region?

Thanks in advance for your reply!

Best regards,

Ruud