Impact of the Sub-Grid Scale Turbulence Model in Aeroacoustic Simulation of Human Voice

Abstract

In an aeroacoustic simulation of human voice production, the effect of the sub-grid scale (SGS) model on the acoustic spectrum was investigated. In the first step, incompressible airflow in a 3D model of larynx with vocal folds undergoing prescribed two-degree-of-freedom oscillation was simulated by laminar and Large-Eddy Simulations (LES), using the One-Equation and Wall-Adaptive Local-Eddy (WALE) SGS models. Second, the aeroacoustic sources and the sound propagation in a domain composed of the larynx and vocal tract were computed by the Perturbed Convective Wave Equation (PCWE) for vowels [u:] and [i:]. The results show that the SGS model has a significant impact not only on the flow field, but also on the spectrum of the sound sampled 1 cm downstream of the lips. With the WALE model, which is known to handle the near-wall and high-shear regions more precisely, the simulations predict significantly higher peak volumetric flow rates of air than those of the One-Equation model, only slightly lower than the laminar simulation. The usage of the WALE SGS model also results in higher sound pressure levels of the higher harmonic frequencies.

Aeroacoustic formulations for confined flows based on incompressible flow data

“…Figure 8 presents spectra of the full Lighthill source term together with the resolved and the SGS contribution at an arbitrarily chosen position (y = À0.15D, z = À0.73D) inside the highly turbulent region downstream of the orifice, indicated by the cross in Figure 8d. The amplitudes of the SGS contribution to the Lighthill source term are consistently one order of magnitude smaller than the resolved contribution up to frequencies of f % 10 kHz, which demonstrates their quantitative irrelevance in the full Lighthill source term, as also shown in [55]. This is also true for the case C3 with the highest Reynolds number, where the modelled unresolved part of the turbulent kinetic energy is largest.…”

Computational aeroacoustics of the EAA benchmark case of an axial fan

“…These fast and accurate algorithms are implemented in the open-source software openCFS (openCFS.org, [37]). Since then, several low Mach number flow applications have been addressed by computational aeroacoustics using the PCWE model successfully [5,14,23,52,60,65,69,72,182,141]. Recently, we proved that the fluid motion and acoustics can be separated inside the source region [29] and showed that the definition of the acoustic variable is valid for incompressible flows [29].…”

Special Issue on Computational Methods and Engineering Solutions to Voice II

“…They conclude from their study that turbulent structures increase the broadband component of the voice signal, supporting previous assumptions on the effect of glottal closure and glottal insufficiency. Lasota et al [9] investigate the impact of the Sub-Grid Scale (SGS) turbulence model in aero acoustic simulations. Finally, Rosenthal et al [10] investigate the mechanics of straw phonation, introducing a new electrical circuit-based model of the vocal tract as a transmission line as counterpart for CFD modelling.…”