Aerosol Deposition Efficiencies and Upstream Release Positions for Different Inhalation Modes in an Upper Bronchial Airway Model

Accurate predictions of micron-particle deposition patterns and surface concentrations in lung airways are most desirable for researchers assessing health effects of toxic particles or those concerned with inhalation delivery of therapeutic aerosols. Focusing on a rigid, symmetric triple bifurcation lung airway model, i.e., Weibel's generations G3-G6, a user-enhanced and experimentally validated finite volume program has been employed to simulate the airflow and particle transport under transient laminar three-dimensional flow conditions. Specifically, the effects of 3 inhalation modes, i.e., resting and light and moderate activities, were analyzed for typical ranges of Stokes numbers (St h 0.2) and Reynolds numbers (0 h Re h 2100). The detailed results show particle deposition patterns and efficiencies in the triple bifurcation under cyclic as well as steady-state inhalation conditions. Cyclic inhalation generates higher local and segmentally-averaged deposition rates when compared to steady mean Reynolds number inhalation; however, matching Stokes and Reynolds numbers, i.e., the average between mean and peak values, were found to provide fully equivalent results for all inhalation modes and bifurcations. In addition, particle maps were developed that show the release positions of deposited aerosols.