Boundary Type

H-Field Behavior

Used to model...

Default Boundary Conditions (Natural and Neumann)

Field behaves as follows:

• At the interface between objects, the H tangent and B normal are continuous.
• On outer boundaries, B field is normal. As a rule, this behavior needs to be modified at least for some portions of the outer boundary to insure uniqueness of the solution.

Initially, object interfaces are natural boundaries; outer boundaries, and excluded objects are Neumann boundaries.

Vector Potential

Sets the magnetic vector potential A_z, or rA_f, on the boundary. The behavior of H depends on whether A_z or rA_f is constant or functional.

Outer boundaries at specific vector potentials; externally applied magnetic fields.

Balloon

This boundary is considered to be far away from the other sources in the problem.

Actual behavior is context dependent. In general, if a Dirichlet BC is not applied elsewhere to insure uniqueness, the "balloon" will be assigned a Dirichlet boundary condition.

Symmetry

Field behaves as follows:

• Odd Symmetry (Flux Tangential) — Magnetic Field is tangential to the boundary; its normal components are zero.
• Even Symmetry (Flux Normal) — Magnetic Field is normal to the boundary; its tangential components are zero.

Planes of geometric and magnetic symmetry.

Matching

(Independent and Dependent)

The Magnetic Field vector on the dependent boundary is forced to match the magnitude and direction (or the negative of the direction) of the Magnetic Field vector on the independent boundary.

Planes of symmetry in periodic structures where Magnetic Field is oblique to the boundary.