An adjustable triple-bifurcation unit model for air-particle flow simulations in human tracheobronchial airways

A new methodology for a swift and accurate computer simulation of large segments of the human lung airways is presented. Focusing on a representative tracheobronchial (TB) region, i.e., G0-G15, nano- and micron particle transports have been simulated for Q(in)=30 lmin, employing an experimentally validated computer model. The TB tree was geometrically decomposed into triple-bifurcation units with kinematically adjusted multilevel outlet/inlet conditions. Deposition patterns and maximum concentrations differ greatly between nanoparticles (1< or =d(p)< or =150 nm) and micron particles (1< or =d(p)< or =10 microm), which may relate uniquely to health impacts. In comparison with semi-analytical particle deposition results, it is shown that such simple "lung models" cannot predict local deposition values but can match computer simulation results for the entire TB region within 2.5-26%. The present study revealed that turbulent air-particle flow may propagate to G5 for the assumed inhalation flow rate. Geometry and upstream effects are more pronounced for micron particle deposition than for nanoparticle deposition.