The Effect of Convective Mixing on Particle Transport in the Human Respiratory Tract

Abstract

Aerosol inhalation studies have demonstrated the significance of convective mixing for gas and particle transport in the lungs. Convective mixing can be determined experimentally by measuring as a function of volumetric depth the dispersion of an aerosol bolus while this bolus penetrates into a defined lung volume during inspiration and is recovered from this depth upon expiration. Since convective mixing may be influenced by the variability and asymmetry of the branching airway geometry, a recently developed model of aerosol transport in a random airway system has been applied to study aerosol bolus dispersion. The effect of convective mixing has been considered in effect by diffusivity. It modifies the penetration of individual particles into the lung, the time distribution of exhaled particles, and mixing in the alveolar region, finally resulting in the experimentally observed dispersion of a narrow inhaled aerosol bolus.