8 research outputs found
Convergence of the uniaxial PML method for time-domain electromagnetic scattering problems
In this paper, we propose and study the uniaxial perfectly matched layer
(PML) method for three-dimensional time-domain electromagnetic scattering
problems, which has a great advantage over the spherical one in dealing with
problems involving anisotropic scatterers. The truncated uniaxial PML problem
is proved to be well-posed and stable, based on the Laplace transform technique
and the energy method. Moreover, the -norm and -norm error
estimates in time are given between the solutions of the original scattering
problem and the truncated PML problem, leading to the exponential convergence
of the time-domain uniaxial PML method in terms of the thickness and absorbing
parameters of the PML layer. The proof depends on the error analysis between
the EtM operators for the original scattering problem and the truncated PML
problem, which is different from our previous work (SIAM J. Numer. Anal. 58(3)
(2020), 1918-1940).Comment: 23 pages, 1 figure. arXiv admin note: text overlap with
arXiv:1907.0890
On stability of discretizations of the Helmholtz equation (extended version)
We review the stability properties of several discretizations of the
Helmholtz equation at large wavenumbers. For a model problem in a polygon, a
complete -explicit stability (including -explicit stability of the
continuous problem) and convergence theory for high order finite element
methods is developed. In particular, quasi-optimality is shown for a fixed
number of degrees of freedom per wavelength if the mesh size and the
approximation order are selected such that is sufficiently small and
, and, additionally, appropriate mesh refinement is used near
the vertices. We also review the stability properties of two classes of
numerical schemes that use piecewise solutions of the homogeneous Helmholtz
equation, namely, Least Squares methods and Discontinuous Galerkin (DG)
methods. The latter includes the Ultra Weak Variational Formulation