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. 2009 Nov 16;64(22):4640-4648.
doi: 10.1016/j.ces.2009.05.017.

Ozone Uptake During Inspiratory Flow in a Model of the Larynx, Trachea and Primary Bronchial Bifurcation

Amit Padaki  1 , James S Ultman, Ali Borhan
Affiliations

Ozone Uptake During Inspiratory Flow in a Model of the Larynx, Trachea and Primary Bronchial Bifurcation

Amit Padaki et al. Chem Eng Sci. .

Abstract

Three-dimensional simulations of the transport and uptake of a reactive gas such as O(3) were compared between an idealized model of the larynx, trachea, and first bifurcation and a second "control" model in which the larynx was replaced by an equivalent, cylindrical, tube segment. The Navier-Stokes equations, Spalart-Allmaras turbulence equation, and convection-diffusion equation were implemented at conditions reflecting inhalation into an adult human lung. Simulation results were used to analyze axial velocity, turbulent viscosity, local fractional uptake, and regional uptake. Axial velocity data revealed a strong laryngeal jet with a reattachment point in the proximal trachea. Turbulent viscosity data indicated that jet turbulence occurred only at high Reynolds numbers and was attenuated by the first bifurcation. Local fractional uptake data affirmed hotspots previously reported at the first carina, and suggested additional hotspots at the glottal constriction and jet reattachment point in the proximal trachea. These laryngeal effects strongly depended on inlet Reynolds number, with maximal effects (approaching 15%) occurring at maximal inlet flow rates. While the increase in the regional uptake caused by the larynx subsided by the end of the model, the effect of the larynx on cumulative uptake persisted further downstream. These results suggest that with prolonged exposure to a reactive gas, entire regions of the larynx and proximal trachea could show signs of tissue injury.

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Figures

Figure 1
Figure 1
Coronal (upper panel) and sagittal (lower panel) views of idealized larynx model mesh.
Figure 2
Figure 2
Coronal (upper panel) and sagittal (lower panel) views of tubular control model mesh.
Figure 3
Figure 3
Contours of dimensionless axial velocity in the coronal cross-sectional of the tubular control.
Figure 4
Figure 4
Contours of dimensionless axial velocity in the coronal cross-sectional of the idealized larynx.
Figure 5
Figure 5
Cross-sectional averages of dimensionless axial velocity for the idealized larynx and tubular control models, and the numerical difference between them.
Figure 6
Figure 6
Cross-sectional averages of turbulent viscosity ratio for the idealized larynx and tubular control models, and the numerical difference between them.
Figure 7
Figure 7
Color map of local fractional uptake in the tubular control.
Figure 8
Figure 8
Color map of local fractional uptake in the idealized larynx.
Figure 9
Figure 9
Cross-sectional averages of local fractional uptake for the idealized larynx and tubular control models, and the numerical difference between them.
See this image and copyright information in PMC

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