Particle deposition in the human tracheobronchial airways due to transient inspiratory flow patterns

Abstract Considering realistic tracheobronchial airways, transient airflow structures and micro-particle deposition patterns were simulated with an in-house finite-volume code for typical inhalation waveforms and Stokes numbers, i.e., the average flow rates at the trachea inlet, Q in , av , are 15 and 60 L / min and the mean Stokes number at the trachea inlet, St mean , trachea , is in the range of 0.0229 ⩽ St mean , trachea ⩽ 0.0915 , respectively. While the overall airflow fields exhibit similar characteristics, the local flow patterns which influence particle deposition are largely affected by secondary flows (for both Q in , av = 15 and 60 L / min ) as well as airflow turbulence (when Q in , av = 60 L / min ). The particle deposition fraction is a strongly transient function according to a given inhalation waveform. In light of the importance of targeted drug-aerosol delivery, it is shown that the relation between particle-release positions at the trachea inlet and particle depositions at specific lung sites are greatly influenced by the complex airway geometry and the flow-rate magnitude. For laminar flow, the particle-release points are deterministic and unique, as required for optimal drug-aerosol targeting.

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