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. 2017 May;31(3):275-281.
doi: 10.1016/j.jvoice.2016.04.006. Epub 2016 May 10.

The Effect of False Vocal Folds on Laryngeal Flow Resistance in a Tubular Three-dimensional Computational Laryngeal Model

Qian Xue  1 , Xudong Zheng  2
Affiliations

The Effect of False Vocal Folds on Laryngeal Flow Resistance in a Tubular Three-dimensional Computational Laryngeal Model

Qian Xue et al. J Voice. 2017 May.

Abstract

Objective: The current study used a three-dimensional (3D) computational laryngeal model to investigate the effect of false vocal folds (FVFs) on laryngeal flow resistance.

Method: A 3D, tubular shaped computational laryngeal model was designed with a high level of realism with respect to the human laryngeal anatomy. Two cases, one with the FVFs and the other without the FVFs, were created in the numerical simulation to compare the laryngeal flow behaviors.

Results and conclusion: The results were discussed in a comparative manner with the previous two-dimensional (2D) computational model. On the one hand, the results demonstrated the similar mechanism as observed in the 2D model that the presence of the FVFs suppressed the deflection of the glottal jet and in doing so, reduced the mixing-related minor loss in the supraglottal region. On the other hand, the 3D flow was more stable and straighter, so the effect of FVFs on suppressing the jet deflection in the 3D model was not as prominent as in the 2D model. Furthermore, the presence of the FVFs also increased the friction-related major loss due to the increased velocity gradient in the restricted flow channel. Therefore, it was hypothesized that the final effect of the FVFs on flow resistance is the combined effect of the reduced mixing-related minor loss and increased friction-related major loss, both of which are highly related to the gap between the FVFs.

Keywords: Computational laryngeal model; False vocal folds; Glottal jet deflection; Laryngeal flow resistance; Three-dimensional glottal flow dynamics.

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Figures

Figure 1
Figure 1
(a) The computational domain and laryngeal model; (b) The mid-coronal plane of the laryngeal model; The dash lines and dots indicate the location of the measurements in Figure 6 and Figure 7; (c) The superior view of the geometrical model; (d) Dimensions of the FVF; (e) The three-layer inner structure of the TVF. Color online.
Figure 2
Figure 2
Time history of the glottal volume flow rate of the two cases.
Figure 3
Figure 3
Frequency spectrum of the glottal flow rate over the sustained vibration stage of the two cases.
Figure 4
Figure 4
Contour of the velocity magnitude at the center plane of the larynx at phases 1, 3, 5, 7, 11 and 13. The phases are indicated in a typical glottal flow waveform. Color online.
Figure 5
Figure 5
Contour of the turbulent kinetic energy at the mid-coronal plane at the same phases as in Figure 4 for the two cases. Color online.
Figure 6
Figure 6
The streamwise velocity of the time-averaged flow across the channel at two locations at Y=3.2 cm (near glottis exit) and Y=4.0 cm (near minimum FVFs gap) for the two cases. Color online.
Figure 7
Figure 7
The time averaged pressure and velocity distribution along the flow direction at the centerline of the larynx for the two cases
See this image and copyright information in PMC

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