Hybrid non-uniform grid based fast global boundary conditions for concave scatterers

We present a novel fast iterative algorithm (NG fast GBC) based on a hybrid boundary integral formulation. When coupled with domain decomposition and a non-uniform polar grid interpolation scheme, it has the potential to overcome some of the limitations of local absorbing boundary condition (ABC) schemes. The algorithm applies to scattering problems for bodies with arbitrarily shaped exterior boundaries and allows significant reduction in "white space". In our formulation, the scatterer is assumed as PEC, although extension of the scheme to arbitrary local boundary conditions (e.g., impedance boundary) is quite possible. An efficient and accurate multidimensional interpolation scheme serves as key to the implementation of the method, especially if the technique is employed in a multilevel computational scheme.