Computational Fluid Dynamics Study of Airflow and Microparticle Deposition in a Constricted Pharyngeal Section Representing Obstructive Sleep Apnea Disease

Developing a computational model to predict the abnormal flow characteristics and particle deposition produced by obstructive sleep apnea is an important step in learning the pathophysiology of Obstructive Sleep Apnea (OSA) disease. The objectives of this study are to investigate the airflow characteristics in the constricted airway region where obstruction could occur and to investigate the effect of abnormal airflow characteristics and microparticle deposition in the breathing airway due to pharyngeal occlusion. In this study, Computational Fluid Dynamics (CFD) analysis has been performed on an upper airway computational model with a constricted pharyngeal section representing Obstructive Sleep Apnea (OSA) disease. The different breathing rates of laminar and turbulent inspiratory airflows were simulated numerically through the upper airway model. The airflow characteristics and pressure distribution were analysed. A Lagrangian trajectory analysis approach was used to examine the transport and deposition of the injected microparticles through the nasal airways. The deposition fraction of the microparticles in a specific region through the upper airway model are presented. The results show that the morphology of the upper airway was found to significantly affect the airflow pattern and the deposition fraction of the microparticles. It was observed that, as the diameter of the particle increases, the location of the highest particle deposited will shift to the anterior part of the upper airway. The local deposition fractions proved that the upper airway plays a significant role in filtering large micro-particles.