Magnetic Scalar-Scalar Potential Coupling
The Magnetic Scalar-Scalar Potential Coupling multiphysics node assures continuity of the magnetic scalar potential across boundaries between The Magnetic Fields, No Currents Interface and The Magnetic Fields, No Currents, Boundary Elements Interface. The Magnetic Scalar-Scalar Potential Coupling node is available from the Multiphysics menu in the Physics toolbar or by right-clicking the Multiphysics Couplings node in Model Builder, if both The Magnetic Fields, No Currents Interface and The Magnetic Fields, No Currents, Boundary Elements Interface are available.
The Magnetic Fields, No Currents Interface can be set to solve for the Reduced field using the Background Magnetic Field setting. The Magnetic Fields, No Currents, Boundary Elements Interface does not have such a setting but it can be made to represent an open boundary for the reduced field by adding, in The Magnetic Fields, No Currents Interface, an External Magnetic Flux Density feature on the boundary selection for the Magnetic Scalar-Scalar Potential Coupling.
When using The Magnetic Fields, No Currents, Boundary Elements Interface with iterative solvers, Right Preconditioning is preferred. Thus, it is advised to check that Right Preconditioning is used when combining the Magnetic Scalar-Scalar Potential Coupling with The Magnetic Fields, No Currents, Boundary Elements Interface and other physics interfaces. How to define Right Preconditioning is described in Iterative in the COMSOL Multiphysics Reference Manual.
boundary selection
Select Manual or All boundaries from the Selection list. Make additional edits to the list of boundary entity numbers using the Selection toolbar buttons. When All boundaries is selected from the Selection list, the boundaries exterior to the Magnetic Fields, No Currents interface that intersect the exterior boundaries to the Magnetic Fields, No Currents, Boundary Elements interface are available in the boundary entity number list.
When using the symmetry options at the physics interface level as discussed in Symmetry, there will be no degrees of freedom on the symmetry planes. For such cases, please make sure that the coupling selection does not contain boundaries that intersect with the symmetry planes.
coupled interfaces
Select Magnetic Fields, No Currents as Primary interface and Magnetic Fields, No Currents, Boundary Elements as Secondary interface.