Deposition of Evaporating Microdroplets Near a Stagnation Point

Respiratory droplets that can transmit infections were the subject of many recent studies which had a strong impact on understanding human respiratory diseases. In particular, trajectories and deposition locations of microdroplets in respiratory airways have been investigated. In the present study, we investigate the deposition of microdroplets near a stagnation point in the respiratory airway. Our model accounts for the presence of boundary layers in both vapor density distribution and moist air flow field. We consider evaporation on the droplet surface that reduces the size of the droplet as it travels through the region of varying vapor density and describe how evaporation changes the droplet trajectories and the deposition patterns at the wall of the respiratory airway. Droplets are found to be deposited further away from the stagnation point as their size is reduced by evaporation.