A surface impedance method for 3D time transient problems

A new technique for modelling time transient thin skin depth eddy currents is presented. The non conducting regions are modelled using conventional vo lume finite elements in terms of the magnetic scalar potential psi, The mag netic 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 tr ansient solution to the two sets of equations in psi and A is then carried out. A finite element implementation and some test examples are described.