SYNTHESIS OF A WIDE-BAND, GLOBAL BOUNDARY-CONDITION BASED ON THE RECIPROCITY THEOREM FOR FINITE-ELEMENT ANALYSIS

Two broad categories of absorbing boundary conditions (ABCs) are typic ally utilized in the finite-element method (FEM) for mesh truncation. The first class of hybrid techniques, which are global and rigorous in nature, cause the augmented FEM system matrix to exhibit a loss of sp arsity. In the second class of ABCs, which are strictly local but appr oximate in character, the sparsity of the FEM system matrix is preserv ed at the expense of numerical accuracy In this article we synthesize a novel wideband boundary condition based on an application of the rec iprocity theorem. Although this boundary condition is essentially glob al in nature, it tends to maintain the sparsity of the FEM matrix to t he same extent that the numerical ABCs (NABCs) do. (C) 1996 John Wiley & Sons, Inc.