Fluid-particle dynamics of nasal drug delivery in a realistic human airway lung model

![CDATA[Nasal drug delivery provides a rapid onset of therapeutic effects due to the nasal route's large surface area, high blood flow, and ease of accessibility. As a result, intranasal drug delivery preventions and treatments for lung diseases are becoming more prominent, especially with the emergence and prevalence of COVID-19. However, there is a lack of fundamental knowledge on the exact particle distribution and deposition in a whole human airway model, extending from the nasal and oral cavity to the terminal bronchioles. This study reconstructs a realistic airway surface geometry from thin-layered computed tomography scans (using Mimics Medical) to explore and understand nasal drug trajectories. The model extends from the nasal and oral cavity to the terminal bronchioles, reaching a maximum of 14 generations. Geomagic Warp, UG NX 12, and ANSYS are used for geometric post-processing, mesh generation, and fluid-particle simulation. In this study, a total of 8741 micron-sized particles (1 µm) are released into the nasal cavity with a jet effect resembling a nasal spray for a duration of 1s. The inhalation nasal velocity corresponds to a realistic breathing velocity profile. Results reveal the vorticity generation in the pharynx-to-larynx region directly before reaching the trachea. In addition, the trajectory and deposition of particles are demonstrated in the whole lung along with their velocity magnitudes. Through this study, intranasal drug delivery studies will be able to observe airflow behavior and 1 µm particle trajectories inside the lungs.]]