The effect of gravity on particle deposition patterns in bronchial airway bifurcations

Inspiratory particle deposition patterns within three-dimensional models of asymmetric bronchial airway bifurcations in the human lungs are simulated by a numerical model in which the Navier-Stokes equations for the air velocity field are solved by numerical methods and trajectories of aerosol particles entrained in the airstream are modeled by Monte Carlo techniques. In this note, the effect of the spatial orientation of a bronchial bifurcation relative to the gravity vector has been explored for situations where gravitational settling is the primary mode of particle deposition. Resulting inspiratory deposition patterns and efficiencies for five different orientations are distinctly different from each other, emphasizing the significance of the gravity angle for the determination of localized doses and their distribution among different regions of the human lungs.