Improvement of the performance of the BGT2 condition for low frequency acoustic scattering problems

We propose to incorporate a damping effect to the second-order Bayliss-Gunzburger-Turkel local absorbing boundary condition (BGT2) in order to extend the range of satisfactory performance when employed on elliptical-shaped artificial boundaries for solving low frequency acoustic scattering problems. This damping procedure consists simply in adding a constant imaginary part to the wavenumber. We investigate the performance of the modified condition in the OSRC formulation context. The numerical results reported here reveal that the modified version of BGT2 extends the range of satisfactory performance by improving the level of accuracy by up to two orders of magnitude. Guidelines on the appropriate choice of the damping coefficient are provided.