Flow behavior in idealized & realistic upper airway geometries.

This study investigated the flow characteristics in idealized and realistic upper airway models during oral inhalation, focusing on their ability to replicate airflow dynamics and turbulence that impact pharmaceutical aerosol delivery. While idealized airway models, such as the United States Pharmacopeia (USP) model, are widely used in regulatory testing, they lack anatomical fidelity, potentially underestimating critical features, including the laryngeal jet formation, which are essential for accurate particle deposition predictions. Understanding the implications of idealized and realistic models is addressed using Large Eddy Simulations (LES) at inhalation rates of 15 and 30 L/min. Four airway models were analyzed: the USP model, the Virginia Commonwealth University (VCU) model, and two realistic models reconstructed from CT scans of healthy adults. The findings revealed the limitations of the USP model, while the VCU models demonstrated laminar flow behavior with a laryngeal jet with a lower magnitude compared to the realistic models. The realistic models (R01 and R02) exhibited more complex flow features, including an earlier laryngeal jet formation, emphasizing the importance in understanding the limitations of idealized models and the variations between realistic models.