Numerical Simulations of Inlet and Outlet Air Flow Dynamics in Healthy and Stenotic Adult Airway

Most numerical studies of airflow resistance in the lungs have presented flow dynamics in different stenosis tracheobronchial airway generations. However, not much is known about the airflow characteristics in conditions where stenoses are present at both the airflow inlet and out letregions, especially in truncated tracheobronchial airway models. In this study, we constructed a healthy adult airway model and two stenosed airway models made up of generation six to nine (G6-G9). Computational Fluid Dynamics (CFD) simulations were performed in all airway models to investigate the airflow characteristics. We made comparison between the inlet and outlet air flow dynamics in the healthy and stenosis models during inspiration and expiration to understand if airflow resistance was higher in the upper or lower stenosis airway.Airflow velocity and wall shear stress were greater in the upper airway (G6) for both inspiration and expiration, while wall pressure was highest in the lower airway (G9). The airflow velocities in obstructed upper tracheobronchial airways during inspiration and expiration were about 3.84 m/ sand 1.49 m/s greater than in the lower airways during same respiratory cycle, respectively. The quantitative information in this study shows that stenosis at the lower airway generation has more effect on respiratory airflow than in the upper airway generations.