A domain decomposition approach for non-conformal couplings between finite and boundary elements for unbounded electromagnetic problems in

This paper presents a symmetric FEM–BEM formulation for solving unbounded three-dimensional electromagnetic problems. The approach is based on domain decomposition method that decomposes original problem into FEM and BEM domains. Two domains communicate through Robin transmission condition enforced on the interface between these two domains. The meshes on the interface are non-matching (non-conformal), thus two domains can be modularly treated. The resulting system matrix is symmetric and free of internal resonances. To accelerate the convergence of iterative solvers, three Schwarz type preconditioners are proposed. An ad hoc proof of convergence for the proposed Robin interface between FEM and BEM is also included for spherical outer boundaries. The efficiency and performance of the proposed approach with three different preconditioners are demonstrated through a few numerical examples.