Anisotropic Minimum Dissipation Subgrid-Scale Model in Hybrid Aeroacoustic simulations of Human Phonation

TL;DR

This study introduces an anisotropic minimum dissipation subgrid-scale model for large-eddy simulations of human phonation, demonstrating improved acoustic predictions and formant accuracy in aeroacoustic simulations of vowels.

Contribution

The paper develops and implements a novel anisotropic subgrid-scale model in OpenFOAM, enhancing the accuracy of aeroacoustic simulations of human speech production.

Findings

The new model predicts stronger sound pressure levels at higher harmonics.

It improves the accuracy of formant position predictions.

Numerical results agree well with experimental measurements.

Abstract

This article deals with large-eddy simulations of 3D incompressible laryngeal flow followed by acoustic simulations of human phonation of five cardinal english vowels /u, i, \textipa{A}, o, {\ae}/. The flow and aeroacoustic simulations were performed in OpenFOAM and in-house code openCFS, respectively. Given the large variety of scales in the flow and acoustics, the simulation is separated into two steps: (1) computing the flow in the larynx using the finite volume method on a fine 2.2M grid followed by (2) computing the sound sources separately and wave propagation to the radiation zone around the mouth using the finite element method on a coarse 33k acoustic grid. The numerical results showed that the anisotropic minimum dissipation model, which is not well known since it is not available in common CFD software, predicted stronger sound pressure levels at higher harmonics and especially at first two formants than the wall-adapting local eddy-viscosity model. We implemented the model as a new open library in OpenFOAM and deployed the model on turbulent flow in the larynx with positive impact on the quality of simulated vowels. Numerical simulations are in very good agreement with positions of formants from measurements.