Microscopic behavior of the solutions of a transmission problem for the Helmholtz equation. A functional analytic approach


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Akyel T., de Cristoforis M. L.

Studia Universitatis Babes-Bolyai Mathematica, cilt.67, sa.2, ss.383-402, 2022 (Scopus)

Özet

Let Ωi, Ωo be bounded open connected subsets of Rn that contain the origin. Let (Formula Presented) for small ε > 0. Then we consider a linear transmission problem for the Helmholtz equation in the pair of domains ε Ωi and Ω(ε) with Neumann boundary conditions on ∂Ωo. Under appropriate conditions on the wave numbers in ε Ωi and Ω(ε) and on the parameters involved in the transmission conditions on ε Ωi, the transmission problem has a unique solution (Formula Presented) for small values of ε > 0. Here ui(ε,.) and uo(ε,.) solve the Helmholtz equation in ε Ωi and Ω(ε), respectively. Then we prove that if (Formula Presented)and (Formula Presented) then the rescaled solutions (Formula Presented) and (Formula Presented) can be expanded into a convergent power expansion of (Formula Presented) for ε small enough. Here kn = 1 if n is even and kn = 0 if n is odd and δ2,2 ≡ 1 and δ2,n ≡ 0 if n ≥ 3.