Self-adapting absorbing boundary conditions for the wave equation

In this paper, we introduce a self-adapting absorbing boundary condition for the linear wave equation. The construction is based on a local computation of the incidence angle of the outgoing wave and on the use of the classical lowest order Engquist-Majda absorbing boundary condition. In order to obtain a good approximation of the incidence angle, we decompose adaptively the absorbing boundary into subsegments and apply locally the Fourier transformation. Numerical results illustrate the performance of the newly designed self-adapting absorbing boundary condition and show its robustness.