Deposition of Inhaled Particles in Bifurcating Airway Models: I. Inspiratory Deposition

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Abstract
Deposition pattern and efficiency of inhaled particles in bifurcating airways were studied experimentally by using Y-shaped single bifurcation tube models in conjunction with varying branching angles (θ = 15-90°), branching symmetry, and flow distribution pattern between two daughter branches. Monodispersed oil droplets (3, 5 and 7 μm dia.) tagged with uranine were used as test aerosols and sampling flow rate was maintained in the Reynolds number (Re) of 1132-3397. The model tubes were washed section by section with deionized water and the fluorescence content in the washed solution was used for determining deposition efficiency. Particle deposition occurred mainly near the bifurcation and increased with increasing Stokes number (StK). Deposition efficiency did not change with branching angle for θ = 15-45° but increased somewhat for the extreme branching angles of 60° and 90°. Branching asymmetry and flow distribution pattern did not affect the deposition efficiency within the range tested. From these results, a unified formula for deposition efficiency was derived as a single function of Stokes number and compared with theoretical predictions and previous experimental results.