SOME FORMULATIONS COUPLING FINITE-ELEMENT AND INTEGRAL-EQUATION METHODS FOR HELMHOLTZ-EQUATION AND ELECTROMAGNETISM

In this paper a study of the coupling between integral equations and f inite element methods is presented for two problems of propagation in frequency domain. It is shown that these problems can be viewed as mul tidomain problems and treated by the mean of the Schur complement tech nique. The complement coming from the integral equation part is expres sed with the integral operators of the scattering theory. This allows to predict the behaviour of the Schur method, either primal or dual, a s far as its convergence speed is concerned. Furthermore, the differen ce of behaviour between electromagnetism and acoustics from this point of view is explained.