Final appearance of the respiratory model employed in the experiments
In this study, the deposition of particles (0.3 mm to 2.5 mm in
diameter) within a silicone rubber model of the human upper respiratory system was
studied. The domain of the respiratory tract under investigation begins at the
entrance (nostrils and mouth) and continues through to the second generation of the
tracheobronchial airways (mainbronchi). The particle deposition efficiency of the sample
respiratory system was computed by measuring particle concentration at the inlet and
outlet of the model. The regional deposition patterns of fluorescent particles (0.3
mm to 0.7 mm in diameter) was examined by measuring the fluorescent intensity with a
fluorescence spectrophotometer. For simulated oral inhalation, the deposition
efficiency of the oral cavity (0.9% - 5.4%) is approximately the same as that of the
oropharynx-trachea region (0.8% - 4.8%). During simulated nasal inhalation, the
deposition efficiency of the nasal region (20% - 43.6%) is greater than the values of the
nasopharynx-trachea region (2.8% - 8.2%). The nasopharynx-trachea region exhibits a
higher deposition efficiency than that of the oropharynx-trachea region. Deposition
during the simultaneous oral and nasal inhalation is mostly affected by particle
size. Flow rate through the model has less effect on deposition for particle
diameter less than 1 mm. When particle diameter is greater than 1 mm,
deposition efficiencies are weakly and inversely related to the flow rate.
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Biofluids and Heat Transfer Laboratory
Mechanical Engineering and Applied Mechanics
University of Rhode Island