Fluid Dynamics of the Human Larynx and Upper Tracheobronchial Airways

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Abstract
The deposition sites of inhaled particles must be known to (1) promote therapeutic effects of airborne pharmacologic drugs via targeted delivery and (2) improve risk assessments of ambient contaminants. Because particle trajectories are affected by the motion of an entraining fluid, it is important to determine the character of an inhaled airstream. In this report, an original theory is presented for the simulation of laryngeal and tracheobronchial fluid dynamics. The mathematical model describes conditions in such respiratory tract airways of adult human subjects under various breathing conditions. The data describing fluid dynamics patterns are presented in two formats: graphical displays of mean streamlines and color illustrations of velocity distributions. In the defined airway system, fluid dynamics patterns are heterogeneous. Conditions within the larynx are especially complex, encompassing localized eddies, and a jet formed at the vocal folds. Moreover, the data indicate that the larynx exerts a pronounced influence on flows in distal airways. Fluid motion in the trachea and main bronchi include convective core flows with countercurrents along airway walls. The effects of these flow patterns may be to promote particle deposition at select sites within the larynx and tracheobronchial airways.