The performance of local absorbing boundary conditions for acoustic scattering from elliptical shapes

The computation of exterior wave problems at low wave numbers can become prohibitively expensive when higher circumferential modes are significant, yet local absorbing boundary conditions specified on simple shapes provide satisfactory performance for most scattering problems. An analysis of the effect of wave number and eccentricity on scattering problems, with local absorbing boundary conditions specified on an ellipse and a prolate spheroid as on-surface radiation conditions, shows that at moderate values of eccentricity, good performance extends to relatively low wave numbers. Excessive computational cost may be avoided for many practical applications.