Design of a mode converter using thin resonant ligaments

TL;DR

This paper presents a novel acoustic mode converter design using thin resonant ligaments in a symmetric waveguide, enabling complete mode transmission and conversion through asymptotic analysis and numerical validation.

Contribution

It introduces a new method for designing mode converters with thin ligaments, combining asymptotic analysis and numerical results for optimized energy transmission and mode conversion.

Findings

Complete mode transmission achieved

Mode conversion from mode 1 to mode 2 demonstrated

Design methodology validated by numerical simulations

Abstract

The goal of this work is to design an acoustic mode converter. More precisely, the wave number is chosen so that two modes can propagate. We explain how to construct geometries such that the energy of the modes is completely transmitted and additionally the mode 1 is converted into the mode 2 and conversely. To proceed, we work in a symmetric waveguide made of two branches connected by two thin ligaments whose lengths and positions are carefully tuned. The approach is based on asymptotic analysis for thin ligaments around resonance lengths. We also provide numerical results to illustrate the theory.