A surface impedance method for 3D time transient problems

A new technique for modelling time transient thin skin depth eddy currents is presented. The nonconducting regions are modelled using conventional volume finite elements in terms of the magnetic scalar potential ψ. The magnetic fields in the thin skin are determined approximately using 1D finite elements in terms of magnetic vector potentials, Most problems would result in one large volume matrix and many small 1D matrices. A staggered time transient solution to the two sets of equations in ψ and A is then carried out. A finite element implementation and some test examples are described