Reconstruction of smooth shape defects in waveguides using locally resonant frequencies

TL;DR

This paper introduces a new multi-frequency boundary measurement method to accurately reconstruct smooth, slowly varying width defects in 2D waveguides by exploiting locally resonant frequencies and mode propagation characteristics.

Contribution

The paper presents a novel, explicit, and stable reconstruction technique for waveguide width defects using locally resonant frequencies, validated with numerical data.

Findings

Effective reconstruction of waveguide width defects from boundary data

Method stability demonstrated through numerical validation

Applicable to smooth, slowly varying defects in 2D waveguides

Abstract

This article aims to present a new method to reconstruct slowly varying width defects in 2D waveguides using locally resonant frequencies. At these frequencies, locally resonant modes propagate in the waveguide under the form of Airy functions depending on a parameter called the locally resonant point. In this particular point, the local width of the waveguide is known and its location can be recovered from boundary measurements of the wavefield. Using the same process for different frequencies, we produce a good approximation of the width in all the waveguide. Given multi-frequency measurements taken at the surface of the waveguide, we provide a L \infty-stable explicit method to reconstruct the width of the waveguide. We finally validate our method on numerical data, and we discuss its applications and limits.