INERTIAL AND GRAVITATIONAL DEPOSITION OF PARTICLES IN A SQUARE CROSS-SECTION BIFURCATING AIRWAY

Deposition of spherical particles in an airway bifurcation is studied numerically. Airway dimensions are based on the third airway generatio n of the Weibel symmetric lung model (1963). A square cross-sectional airway area is assumed, with parent and daughter tubes having differen t diameters. The flow field is solved by a finite element method for R eynolds numbers of 100 and 1000 with uniform and parabolic parent inle t velocities. The How field is then used to calculate particle deposit ion in this geometry. Deposition by the mechanisms of impaction and se dimentation are incorporated. The results show that for particles larg er than 10 mum, sedimentation losses are weakly dependent on the flow Reynolds number and the inlet condition, whereas impaction losses depe nd strongly on Reynolds number and inlet condition. Also, the calculat ed results gave good agreement with the predictive model of Pich (1972 ) for sedimentation losses in flows through parallel plates. For losse s by impaction, the calculated results also agreed with the results or Kim and Iglesias (1989) and differed from the theoretical model of Ca i and Yu (1988). Further differences were observed when the current fi ndings were compared with the data of Pui et al. (1991) for particle l oss in a 90-degrees bent, suggesting that geometric features play an i mportant role in deposition of particles.