(37h) A Three-Dimensional Computational Fluid Dynamics Study of Ozone Absorption in the Respiratory Tract

We present the results of numerical simulations of ozone transport and uptake in an anatomically-correct model of the respiratory tract of a Rhesus monkey. The model geometry was created using three-dimensional reconstruction of MRI images of the respiratory tract, including the nasal passages, the larynx, and the first thirteen generations of the tracheobronchial tree. An unstructured mesh was generated for the resulting structure, and three-dimensional flow and concentration distributions were obtained through numerical solution of the Navier-Stokes, continuity, and species convection-diffusion equations. A quasi-steady diffusion-reaction model was used to account for the interaction between O3 and endogenous substrates in the respiratory tract lining fluid. The total rate of ozone uptake within each section of the respiratory tract was determined, and hot spots of ozone flux on the walls were identified. For steady inspiratory flow under quiet breathing conditions, the predicted locations of spikes in ozone flux are consistent with existing experimental observations of the focal sites of epithelial damage in rats [Postlethwait et al., Am. J. Respir. Cell Molec. Biol. 22:191-199, 2000].