Spectral Element Method for the Elastic/Acoustic Waveguide Problem in Anisotropic Metamaterials

TL;DR

This paper introduces a novel spectral element method for simulating elastic and acoustic waveguides in anisotropic metamaterials, enabling accurate and efficient analysis of complex wave propagation phenomena not accessible with traditional methods.

Contribution

The paper develops the first spectral element method tailored for anisotropic metamaterial waveguides, addressing limitations of existing FEM approaches in handling anisotropic densities and negative index parameters.

Findings

Spectral element method achieves higher accuracy than FEM.

The method efficiently simulates waveguides with anisotropic and negative index properties.

Numerical examples confirm the method's advantages in accuracy and computational efficiency.

Abstract

In order to simulate elastic wave propagation in a complex structure with inhomogeneous media, we often need to obtain the propagating eigenmodes of an elastic waveguide. As the waveguide is assumed uniform in one direction, the original 3-D problem can be converted into a so-called 2.5-D problem by using the Fourier transform in that direction. However, the introduction of elastic metamaterials (EMM) broadens the horizon of this subject, and new features are required in EMM waveguides that cannot be obtained by most traditional waveguide solvers. In this work, a spectral element method (SEM) is developed to simulate the elastic/acoustic waveguide problem in anisotropic media with anisotropic mass density and/or negative index parameters. To the best of our knowledge, the SEM has not been introduced previously for such a waveguide problem. For waveguides with anisotropic density that cannot be solved by the FEM in most of commercial software packages, we design an anisotropic density EMM waveguide with our SEM solver to demonstrate some intriguing phenomena. The spectral element results are verified by several numerical examples through comparison with the traditional finite element method (FEM) to show its significant advantages in term of accuracy and computation efficiency.