Simulation of airflow fields and microparticle deposition in realistic human lung airway models. Part II: Particle transport and deposition

In Part II, given the airflow fields discussed in Part I, microparticle deposition for a practical range of Stokes numbers, 0.025⩽St⩽0.102, has been simulated and analyzed, comparing different temporal assumptions, inlet conditions and geometric configurations. The matching steady-state assumption with equivalent Reynolds and Stokes numbers achieves basically the same deposition fraction (DF) values as under transient inhalation conditions. When comparing parabolic vs. realistic inlet velocity profiles, total DF-values are higher for the parabolic inlet flow for all Stokes numbers. Geometric features, such as out-of-plane configurations and cartilaginous rings in the trachea, further change local deposited microparticle concentrations when compared with simple airway models. Furthermore, significant differences were recorded when comparing DFs in some branches of the present realistic model and the Weibel Type A model. For practical purposes, algebraic microparticle-deposition correlations, DF=DF(Re,St), have been obtained for both the left and right upper lung airways. Based on current research results, the out-of-plane model with tracheal rings and realistic inlet condition is recommended for future work.