no code implementations • 25 Feb 2021 • David Lafontaine, Euan A. Spence, Jared Wunsch
These results allow us to prove new frequency-explicit convergence results for (i) the $hp$-finite-element method applied to the variable coefficient Helmholtz equation in the exterior of a Dirichlet obstacle, when the obstacle and coefficients are analytic, and (ii) the $h$-finite-element method applied to the Helmholtz penetrable-obstacle transmission problem.
Analysis of PDEs Numerical Analysis Numerical Analysis
no code implementations • 6 Jan 2021 • Jeffrey Galkowski, David Lafontaine, Euan A. Spence
We consider approximating the solution of the Helmholtz exterior Dirichlet problem for a nontrapping obstacle, with boundary data coming from plane-wave incidence, by the solution of the corresponding boundary value problem where the exterior domain is truncated and a local absorbing boundary condition coming from a Pad\'e approximation (of arbitrary order) of the Dirichlet-to-Neumann map is imposed on the artificial boundary (recall that the simplest such boundary condition is the impedance boundary condition).
Numerical Analysis Numerical Analysis Analysis of PDEs 35J05, 65N99
no code implementations • 6 Jan 2021 • Jeffrey Galkowski, Pierre Marchand, Euan A. Spence
For the Helmholtz equation posed in the exterior of a Dirichlet obstacle, we prove that if there exists a family of quasimodes (as is the case when the exterior of the obstacle has stable trapped rays), then there exist near-zero eigenvalues of the standard variational formulation of the exterior Dirichlet problem (recall that this formulation involves truncating the exterior domain and applying the exterior Dirichlet-to-Neumann map on the truncation boundary).
Analysis of PDEs Numerical Analysis Numerical Analysis 35J05, 35P15, 35B34, 35P25
