Towards coercive boundary element methods for the wave equation

Abstract

In this note, we discuss the ellipticity of the single layer boundary integral operator for the wave equation in one space dimension. This result not only generalizes the well-known ellipticity of the energetic boundary integral formulation in L 2 , but it also turns out to be a particular case of a recent result on the inf-sup stability of boundary integral operators for the wave equation. Instead of the time derivative in the energetic formulation, we use a modified Hilbert transformation, which allows us to stay in Sobolev spaces of the same order. This results in the applicability of standard boundary element error estimates, which are confirmed by numerical results. Energetic space-time boundary integral equationAs in [1], we consider the Dirichlet boundary value problem for the homogeneous wave equation in the one-dimensional spatial domain Ω = (0, L) with zero initial conditions, and for a given time horizon T > 0,