A finite-element-boundary-integral method for scattering and radiation by two- and three-dimensional structures

A hybrid finite-element-boundary-integral formulation for scattering and radiation by 2-D and 3-D composite structures is described. In contrast to other hybrid techniques involving the finite-element method, the method is in principle exact, and can be implemented using low O(N) amounts of storage. This is of particular importance for large-scale applications, and is a characteristic of the boundary chosen to terminate the finite-element mesh, usually as close to the structure as possible. A general description of the method, without reference to any specific geometry or application, is given. A number of 2-D and 3-D applications are then considered, to demonstrate its accuracy, efficiency, and capabilities. Of particular concern in these applications is the choice of the fictitious boundary enclosing the structure. Boundaries of a certain class lead to convolutional boundary integrals, which can be evaluated by the fast Fourier transform without generating a matrix, thus retaining the O(N) storage requirement.<>