A priori error estimates for a time-dependent boundary element method   for the acoustic wave equation in a half-space
  We investigate a time-domain Galerkin boundary element method for the wave equation outside a Lipschitz obstacle in an absorbing half-space. A priori estimates are presented for both closed surfaces and screens, and we discuss the relevant properties of anisotropic Sobolev spaces and the boundary integral operators between them. 
Heiko Gimperlein, Zouhair Nezhi, Ernst P. Stephan
math.NA math.AP