A wave based method for computing high-frequency radiation

International audienceThe calculation of high-frequency wave radiations in exterior domains by finite element methods can lead to large computations. Boundary conditions have to be applied on the surface of the radiating body or on a truncated domain to approximate the behaviour of an infinite domain. In this paper, a different waveguide approach is proposed for computing wave radiation. Propagation constants and wave modes are computed in a small rib around the radiating body for different frequencies. It is shown that the solutions on the boundary of the radiating body and in the exterior domain can be determined efficiently from this set of waves. The method allows an efficient computation of radiation and scattering solutions by limiting the discretization to a very small part of the exterior domain. The error on the boundary condition can be controlled and the solution converges to the exact solution by using a sufficient number of waves. It is shown that the condition is more efficient for high frequencies and can be complementary of the usual approaches involving simple finite or boundary elements. Analytical and numerical examples are computed to show the accuracy of the method