Combining surface impedance boundary conditions with volume discretisation in time-domain finite-element modeling

In this paper a hybrid approach for considering massive conducting regions in time-domain finite-element modeling is presented. Surface impedance boundary conditions, developed in the time domain as previously proposed by the authors, are adopted so as to allow for high-frequency flux components (in a certain frequency band) without the need for very fine discretisation of the conducting region near its surface. These surface conditions are combined with a coarse FE mesh inside the region for conveying slowly varying flux components. The correct impedance behaviour can thus be obtained in a wide frequency range, from DC flux on. The approach is briefly demonstrated by means of a simple 1D test case.