Study of dynamics of airflow and aerosol transport and deposition in human upper airways using large-eddy simulations

This study employs a large-eddy simulation (LES) strategy to investigate airflow and aerosol dynamics in the human upper airways using a truncated SimInhale configuration. Inflow conditions include three steady inhalation flow rates (14.2, 53.2, and 71 L/min), representing quasi-laminar, moderate, and high turbulence conditions, and a realistic cyclic breathing scenario. Under steady flow, monodisperse (1–10 μm) and polydisperse aerosols are analyzed. The study shows that complex airflow dynamics directly influence aerosol transport and deposition, causing global deposition to increase nonlinearly with particle size and Reynolds number, with the larynx being a primary deposition location in turbulent cases. For the polydisperse analysis using uniform, Gaussian, and Rosin-Rammler distributions, the Rosin-Rammler yielded the lowest deposition, while the uniform had the highest. Simulation of the realistic breathing cycle with monodisperse particles shows that deposition occurs almost entirely during the inspiratory phase, with the expiratory phase acting as a clearance mechanism.