IMPROVED FINITE-ELEMENT METHODS FOR ELASTIC-WAVES

In this work we develop finite element methods for exterior problems o f time-harmonic elastic waves. We employ DtN exterior boundary conditi ons on an artificial boundary to obtain a well-posed equivalent proble m in a bounded region that is suitable for domain-based computation. G alerkin, Galerkin/least-squares and Galerkin/gradient least-squares fi nite element methods are presented. In acoustic wave problems the Gale rkin/least-squares method counters the numerical difficulties that res ult from employing the Galerkin method, but proves to be insufficient for elastic waves. A specialization of the Galerkin/gradient least-squ ares method to problems of elastic waves yields good results. Numerica l tests validate these conclusions. (C) 1998 Elsevier Science S.A. All rights reserved.