Nonreflecting boundary conditions in acoustics for finite element methods based upon off-surface boundary integral equations

An off-surface boundary integral (OSBI) method is presented as a mesh termination scheme for solving large or infinite domain problems of acoustics. By using finite element approximations, the discretized boundary integral equation is used to solve for the Neumann boundary condition term in terms of the Dirichlet boundary condition term which is then substituted into associated finite element formulations. Comparison is made of the new OSBI technique with the DtN method of Givoli and Keller. As shown, the proposed boundary condition is accurate, well suited for use with finite element (FE) methods and competitive with the DtN method.