Analysis of multiple scattering iterations for high-frequency scattering problems. I: the two-dimensional case
We present an analysis of a recently proposed integral-equation method for the solution of high-frequency electromagnetic and acoustic scattering problems that delivers error-controllable solutions in frequency-independent computational times. Within single scattering configurations the method is based on the use of an appropriate ansatz for the unknown surface densities and on suitable extensions of the method of stationary phase. The extension to multiple-scattering configurations, in turn, is attained through consideration of an iterative (Neumann) series that successively accounts for further geometrical wave reflections. As we show, for a collection of two-dimensional (cylindrical) convex obstacles, this series can be rearranged into a sum of periodic orbits (of increasing period), each corresponding to contributions arising from waves that reflect off a fixed subset of scatterers when these are transversed sequentially in a periodic manner. Here, we analyze the properties of these periodic orbits in the high-frequency regime, by deriving precise asymptotic expansions for the “currents” (i.e. the normal derivative of the fields) that they induce on the surface of the obstacles. As we demonstrate these expansions can be used to provide accurate estimates of the rate at which their magnitude decreases with increasing number of reflections, which defines the overall rate of convergence of the multiple-scattering series. Moreover, we show that the detailed asymptotic knowledge of these currents can be used to accelerate this convergence and, thus, to reduce the number of iterations necessary to attain a prescribed accuracy.
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- 5.Bleistein N., Handelsman R.A.: Asymptotic Expansions of Integrals. Dover Publications, New York (1986)Google Scholar
- 10.Chernov, N.I.: Construction of transverse fiberings in multidimensional semidispersed billiards. (Russian) Funktsional. Anal. i Prilozhen. 16(4), 35–46, 96 (1982)Google Scholar
- 23.Hörmander, L.: Pseudo-differential operators and hypoelliptic equations. Singular integrals. In: Proceedings of Sympos. Pure Math., vol. X, pp. 138–183, Chicago, Ill., 1966). Amer. Math. Soc., Providence (1967)Google Scholar
- 38.Sinai Y.G.: Developments of Krylov ideas. An addendum to the book. In: Krylov, N.S. (eds) Works on the Foundations of Statistical Physics, Princeton University Press, Princeton (1979)Google Scholar
- 39.Sherer, S.E., Visbal, M.R.: Time-domain scattering simulations using a high-order overset-grid approach. In: Proc. 2005 IEEE Workshop on Computational Electromagnetics in the Time-Domain, pp. 44–47Google Scholar