Dynamics of cough and particulate behaviour in the human airway

ABSTRACT Computational Fluid Dynamics is used to model airflow and penetrant behaviour under cough reflex in human airway. The airway geometry segment from the oral cavity to the primary bronchi is reconstructed from CT scan images of a human subject in the standing posture. The inlet flow condition is derived from dynamic cough profiles obtained from two subjects. The mathematical model allows the laryngopharyngeal wall of the airway to remodel. A k-ω turbulence model is used to represent the transitional flow. A Lagrangian approach is used to track solid penetrants in the flow field as a function of penetrant size and density. High velocities are predicted at peak expiratory cough phase. The penetrant size significantly influences the particle residence time and drag force is largely responsible for changes in the penetrant momentum. The smaller penetrants act like tracers in the flow and can escape the airway faster than larger penetrants.