Boundary integral equation methods for the solution of scattering and transmission 2D elastodynamic problems

TL;DR

This paper develops and analyzes regularized boundary integral equations and optimized Schwarz methods for 2D elastodynamic scattering and transmission problems, demonstrating improved computational efficiency and high-frequency performance.

Contribution

It introduces new CFIER formulations based on coercive DtN approximations and develops high-order Nyström discretizations with convergence analysis.

Findings

CFIER formulations offer computational savings over classical methods.

High-order Nyström quadratures improve discretization accuracy.

OS methods perform well in high-frequency, high-contrast scenarios.

Abstract

We introduce and analyze various Regularized Combined Field Integral Equations (CFIER) formulations of time-harmonic Navier equations in media with piece-wise constant material properties. These formulations can be derived systematically starting from suitable coercive approximations of Dirichlet-to-Neumann operators (DtN), and we present a periodic pseudodifferential calculus framework within which the well posedness of CIER formulations can be established. We also use the DtN approximations to derive and analyze Optimized Schwarz (OS) methods for the solution of elastodynamics transmission problems. The pseudodifferential calculus we develop in this paper relies on careful singularity splittings of the kernels of Navier boundary integral operators which is also the basis of high-order Nystr\"om quadratures for their discretizations. Based on these high-order discretizations we investigate the rate of convergence of iterative solvers applied to CFIER and OS formulations of scattering and transmission problems. We present a variety of numerical results that illustrate that the CFIER methodology leads to important computational savings over the classical CFIE one, whenever iterative solvers are used for the solution of the ensuing discretized boundary integral equations. Finally, we show that the OS methods are competitive in the high-frequency high-contrast regime.