Stability improvement to BEM/FEM coupling scheme for 2D scalar wave problems

The stability problem appeared in boundary element method/finite element method (BEM/FEM) coupling is discussed in this paper. As the response at time t(n + 1) relates to the excitations and responses at all previous tithes, i.e. response history, BEM is easier to be unstable compared with FEM. The Newmark method for FEM is unconditionally stable, oscillations appeared at any time would decrease step by step as time goes by. But the oscillation history caused by FEM may be big enough to cause stability problems to the BEM scheme which although may be stable when used independently. A new procedure is used in this paper to reduce the oscillation history caused by FEM so that it will not cause stability problem to BEM scheme and further to the coupling BEM/FEM scheme. Numerical examples show that the proposed procedure can improve significantly to the stability of the coupling BEM/FEM scheme and cause little numerical damping. (C) 2002 Elsevier Science Ltd. All rights reserved.