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Article Dans Une Revue SIAM Journal on Mathematical Analysis Année : 2023

Decompositions of High-Frequency Helmholtz Solutions via Functional Calculus, and Application to the Finite Element Method

J. Galkowski
E. Spence
J. Wunsch

Résumé

Over the last 10 years, results from [J. M. Melenk and S. Sauter, Math. Comp., 79 (2010), pp. 1871–1914], [J. M. Melenk and S. Sauter, SIAM J. Numer. Anal., 49 (2011), pp. 1210–1243], [S. Esterhazy and J. M. Melenk, Numerical Analysis of Multiscale Problems, Springer, New York, 2012, pp. 285–324] and [J. M. Melenk, A. Parsania, and S. Sauter, J. Sci. Comput., 57 (2013), pp. 536–581] decomposing high-frequency Helmholtz solutions into “low-” and “high-” frequency components have had a large impact in the numerical analysis of the Helmholtz equation. These results have been proved for the constant-coefficient Helmholtz equation in either the exterior of a Dirichlet obstacle or an interior domain with an impedance boundary condition. Using the Helffer–Sjöstrand functional calculus [B. Helffer and J. Sjöstrand, Schrödinger Operators, Springer, Berlin, 1989, pp. 118–197] this paper proves analogous decompositions for scattering problems fitting into the black-box scattering framework of Sjöstrand and Zworski [J. Amer. Math. Soc., 4 (1991), pp. 729–769] thus covering Helmholtz problems with variable coefficients, impenetrable obstacles, and penetrable obstacles all at once. These results allow us to prove new frequency-explicit convergence results for (i) the hp-finite-element method (hp-FEM) applied to the variable-coefficient Helmholtz equation in the exterior of an analytic Dirichlet obstacle, where the coefficients are analytic in a neighborhood of the obstacle, and (ii) the h-FEM applied to the Helmholtz penetrable-obstacle transmission problem. In particular, the result in (i) shows that the hp-FEM applied to this problem does not suffer from the pollution effect.

Dates et versions

hal-04284806 , version 1 (14-11-2023)

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Citer

J. Galkowski, D. Lafontaine, E. Spence, J. Wunsch. Decompositions of High-Frequency Helmholtz Solutions via Functional Calculus, and Application to the Finite Element Method. SIAM Journal on Mathematical Analysis, 2023, 55 (4), pp.3903-3958. ⟨10.1137/21M1409160⟩. ⟨hal-04284806⟩
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