The Dispersion of Aerosols in Systems of Repeatedly Bifurcating Tubes

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Biomedical and Chemical Engineering


C. S. Wang


respiration, dispersion studies, lungs

Subject Categories

Chemical Engineering


During a respiratory cycle, the air flow in the human lungs is forced to split at each bifurcation on inhalation and rejoined at each junction on exhalation. As a result of breathing, the particles suspended in the air are first distributed to various regions in the lungs and then withdrawn. How the particles are distributed is mainly controlled by four mechanisms: convection, Brownian motion, particle inertia, and gravitational settling, the relative importance of each mechanism being determined by the physical parameters.

The present study is aimed at developing a theoretical model of the dispersion of aerosols in the lungs based on pure convection. The present study has the primary objective of examining the assumption that the inhaled particles are evenly distributed. A better understanding of the aerosol distribution will lead to a more realistic model for calculating local deposition rates. From a practical point of view, a more accurate calculation of local deposition is required to estimate the physiological effects of particulate pollutants in air and to assess the effectiveness of aerosol therapy. In addition, the results of the dispersion study may find applications in the development of diagnostic techniques for detecting the impairment of small airways.


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