Non Uniform Rational B-Splines and Lagrange approximations for time-harmonic acoustic scattering: accuracy and absorbing boundary conditions

In this paper, the performance of finite element method based on Lagrange basis functions and Non Uniform Rational B-Splines (NURBS) Iso-Geometric Analysis (IGA) are systematically studied for solving time-harmonic acoustic scattering problems. To assess their performance, numerical examples presented with truncated absorbing boundary conditions. first two , we eliminate domain truncation error by applying second-order Bayliss-Gunzburger-Turkel (BGT-2) Absorbing Boundary Condition (ABC) modifying exact solution. Hence, calculated is an indicator accuracy in bounded computational no artificial error. Next, apply a higher order local ABC Karp's Wilcox's far-field expansions 2D 3D problems, respectively. The both methods exterior problems compared. introduced auxiliary surface also estimated using corresponding functions. influence various parameters, viz., approximating polynomial, number degrees freedom, wave conditions (BGT-2 terms expansions) convergence rate studied. It inferred that, irrespective IGA yields per degree freedom when compared to conventional basis.