Interference of sound waves in a moving fluid

TL;DR

This paper studies how sound waves propagate in a moving fluid within a randomly corrugated tube, revealing how localization length and transmittance variability depend on fluid velocity and randomness.

Contribution

It provides new insights into the effects of fluid velocity and randomness on sound localization and transmittance in confined fluid systems.

Findings

Localization length is highly sensitive to fluid velocity at low velocities.

At high velocities, localization length becomes constant, independent of frequency and randomness.

The standard deviation of transmittance logarithm is a universal function of its mean, unaffected by fluid velocity.

Abstract

We investigate sound propagation in a moving fluid confined in a randomly corrugated tube. For weak randomness and small fluid velocities $v^{(0)}$, the localization length $\xi$ shows extreme sensitivity to the variation of $v^{(0)}$. In the opposite limit of large fluid velocities, $\xi$ acquires a constant value which is independent of the frequency of the incident sound wave, the degree of randomness and $v^{(0)}$ itself. Finally, we find that the standard deviation $\sigma_{\ln T}$ of the logarithm of transmittance $\ln(T)$ is a universal function of the ensemble average $\langle \ln T\rangle $, which is not affected by the fluid velocity.