2015/11/17 by Wenping Bi, Vincent Pagneux, Bi, Wenping +1 · 1 citation
Engineering · Physics and Astronomy · #Acoustic Wave Phenomena Research #FOS: Physical sciences #Quantum Mechanics and Non-Hermitian Physics #Quantum Physics (quant-ph) #Quantum, superfluid, helium dynamics #quant-ph
paper · pdf · doi:10.48550/arxiv.1511.05508
arxiv created 2015/11/17 · openalex publication_date 2015/11/17 · arxiv updated 2015/11/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In this paper we investigate mode nonorthogonal properties and their effects on the sound power attenuation in a waveguide with impedance boundary conditions. By introducing two quantities: self-nonorthogonality Kp, which measures the nonorthogonality between left and right eigenfunctions of a mode, and mutual-nonorthogonality Sij, which measures the nonorthogonality between modes i and j, two opposite limiting cases are clearly identified in the boundary impedance \mathbb Z plane: one is non-dissipation, i.e., acoustic rigid, pressure-release, and purely reactive impedance; the other is Cremer's optimum impedances which are exceptional points --- a subject has attracted much attention in recent years in different physical domains. Variations along an arbitrary path in the complex boundary impedance plane, Kp and Si,j varies between the two opposite extremes. It is found that Kp and Si,j play crucial roles in sound power attenuation.