Glossary: N
natural boundary
A natural boundary is a boundary condition at the interface between different objects. You do not need to apply this boundary condition yourself, as Maxwell enforces it internally. The natural boundary condition reflects the particular local form of Maxwell's equations at the interface between objects where there is an sudden change in the material properties. When crossing such a surface of discontinuity, Maxwell assumes the following behavior (in average):
- The normal component of B is continuous.
- The normal component of D has a jump equal with the local superficial charge density (on the discontinuity surface).
- The tangent component of H is continuous if there are no current sheets on the discontinuity surface (has a jump equal with the density of the current sheet if they are present on the discontinuity surface), and so on.
Neumann boundary
For magnetic problems with T-Omega formulation, the homogeneous Neumann boundary condition specifies that the normal component of the H field is zero. For magnetic problems with A-Phi formulation, the homogeneous Neumann boundary condition specifies that the tangential component of the H field is zero. In other words, this boundary condition confines the magnetic field within the space of the problem. If the out-most surfaces of the problem region are not assigned any boundary conditions, they automatically receive a Neumann BC. Because of this, as a rule, the solution space (region size) should be chosen such that the respective region walls are not close to field sources (currents and/or permanent magnets); this allows us to assume the field is a tangent at the region limits.
nodes
Nodes normally refer to the vertices of the tetrahedral finite elements. They can also refer to the connection points of branches in an electric circuit (if external circuits are used to drive coils).
nominal design
The original model on which Optimetrics analyses are based.
nonlinear materials
Nonlinear materials are materials with the constitutive relationship being nonlinear (such as is the case of the dependency between B and H for some magnetic materials).