Surface-impedance boundary conditions in time-domain finite-element calculations

The authors propose a novel time-domain extension of the well-known frequency-domain surface-impedance method in computational magnetodynamics. Herein, the 1-D eddy-current problem in a massive conducting region (semi-infinite slab) is considered via a number of exponentially decreasing trigonometric basis functions that cover the relevant skin-depth (or frequency) range of the application at hand. The method is elaborated for the 3-D magnetic-vector-potential formulation and is applied to a simple 2-D test case. Results are shown to converge well to those obtained with an accurate brute-force finite-element (FE) model.