Particle-Laden Cilia-Driven flow*

The upper airways of the respiratory system are lined with a mucosal layer which includes: mucus, periciliary fluid, and beating cilia. The coordinated beating of cilia that propels mucus is called the mucociliary escalator. Impairment of the mucociliary escalator can severely impact respiratory health, even more so when harmful particulates deposit in the upper airways. Existing models of the mucociliary escalator dynamics treat particles as massless tracers, quantifying only the bulk fluid transport arising from the driving cilia movement. The dynamics of suspended particles are investigated here using previously established cilia beat patterns in a one-way coupled fluid-structure interaction model. The effects of biophysical airway parameters (beat frequency and synchrony, periciliary height, and cilia arrangement) are investigated. Specific particle sizes and shapes are also considered. The particle dynamics in the periciliary layer are quantified by evaluating particle transport velocity and residence time. Our findings could aid in selection of medical interventions to modulate particle clearance using readily available pharmacological agents.