Numerical Computation of In-cell Parameters for Multiwire Formalism in FDTD

The finite-difference time-domain method is a very suitable tool to analyse the propagation of, among others, lightning and arcing through new high voltage high power distribution networks in aircraft. This paper presents a numerical method for the computation of the in-cell inductance and in-cell capacitance matrices, required to accurately model wire bundles in a finite-difference time-domain grid. The method extends the multiwire formalism proposed by Bérenger, and enables the inclusion of inhomogeneous media, as well as non-cylindrical conductors. Moreover, the method accurately computes the interactions between closely spaced wires that are neglected by the analytical formulation of Bérenger. The presented method is applied to a testcase that can be compared to Bérenger’s results. Finally, results for a testcase that involves dielectric insulation are given.