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Abstract: The performance of the second-order local approximate DtN boundary condition suggested in is investigated analytically when employed for solving high-frequency exterior Helmholtz problems with elongated scatterers. This study is performed using a domain-based formulation and assuming the scatterer and the exterior artificial boundary to be prolate spheroid. The analysis proves that, in the high-frequency regime, the reflected waves at the artificial boundary decay faster than 1/(ka)15/8, where k is the wavenumber and a is the semi-major axis of this boundary. Numerical results are presented to illustrate the accuracy and the efficiency of the proposed absorbing boundary condition, and to provide guidelines for satisfactory performance. [Copyright &y& Elsevier]

This paper addresses the extension of the Bayliss–Turkel second-order radiation condition to an arbitrarily shaped surface. The derivation is based mainly on the pseudo-differential calculus as well as on the introduction of a criterion providing a precise handling of the approximation process involved in the derivation of the radiation condition. The radiation condition then ranges among the most accurate of those of order two. As a by-product of the derivation, almost all known radiation conditions of order less than or equal to two are recovered and their respective accuracies are compared.