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.