Characteristics of the pulsating jet flow through a dynamic glottal model with a lens-like constriction

Abstract

A computational study of the pulsating jet in a squared channel with a dynamic glottal-shaped constriction is presented. It follows the model experiments of Triep and Brücker (J Acoust Soc Am 127(2):1537-1547, 2010) with the cam-driven model that replicates the dynamic glottal motion in the process of human phonation. The boundary conditions are mapped from the model experiment onto the computational model and the three dimensional time resolved velocity and pressure fields are numerically calculated. This study aims to provide more details of flow separation and pressure distribution in the glottal gap and in the supraglottal flow field. Within the glottal gap a 'vena contracta' effect is generated in the mid-sagittal plane. The flow separation in the mid-coronal plane is therefore delayed to larger diffuser angles which leads to an 'axisswitching' effect from mid-sagittal to mid-coronal plane. The location of flow separation in mid-sagittal cross section moves up-and downwards along the vocal folds surface in streamwise direction. The generated jet shear layer forms a chain of coherent vortex structures within each glottal cycle. These vortices cause characteristic velocity and pressure fluctuations in the supraglottal region, that are in the range of 10-30 times of the fundamental frequency.

Phase-averaged and cycle-to-cycle analysis of jet dynamics in a scaled up vocal-fold model

“…While direct comparison is not possible, data shown here qualitatively agree with those reported in Deverge et al. (2003) and Mattheus & Brücker (2018).

Figure 7.Time traces of ( a ) upstream, ( b ) glottal and ( c ) downstream pressure coefficients for the four oscillation frequencies at Re = 7200.

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“…The phase-averaged starting jet is visible in the DPIV vector field and can be seen curving to the right (downward in the figure) away from the centreline. This is evidence of the Coanda effect, which has been discussed in multiple studies including Triep & Brücker (2010), Mattheus & Brücker (2011, 2018) and Sherman et al. (2019).…”

“…Mongeau et al. (1997), Triep & Brücker (2010), Mattheus & Brücker (2018) and Krane et al. (2007, 2010), among others.…”

“…Since there were no flow measurements, however, they could not examine the full dynamics of the problem. Mattheus & Brücker (2018) also presented a measured transglottal pressure trace, but it was used only to validate their computations.…”

Towards a Clinically Applicable Computational Larynx Model

“…According to Hussain and Husain [70], elliptical jets show switching of the main axes in the cross-sectional plane along their streamwise evolution. This three-dimensional flow phenomenon has also been reported in experimental and numerical larynx models with elliptical glottis shapes [47,48,50,51,71]. In Figure 10, the iso-surfaces of the velocity magnitude (50 m/s) are provided at a representative time instance (0.58 T).…”