Investigation of microdroplet trajectories in respiratory airways

Investigations motivated by respiratory health requirements have been focusing on the inhalation and transport processes of pollutant particles via the human respiratory system. Similar issues arise in the studies of transmission of infectious diseases by respiratory droplets. The understanding of the motion of particles or droplets through the air and their interactions with the mouth, throat, and upper airways has improved as a result of studies on micro- and nanoparticle transport and deposition over the past few decades. However, several aspects of interaction of droplets with air flow in this context are still not well understood. In order to investigate the trajectories and deposition of microdroplets in the respiratory airways, we used an imposed velocity profile of air flow that accounts for both motion of inhaled/exhaled air and evaporation from the wall of the respiratory airway. We track droplet motion depending on their initial location and velocity and investigate the effects of viscous drag and the Saffman force on the microparticle deposition. Application of the general framework we developed to droplets that experience phase change is also discussed.