Micro Particles Transport and Deposition in Realistic Geometry of Human Upper Airways

Realistic geometry of human upper airways from mouth to the end of trachea was reconstructed by implementing the CT-Scan images of a male subject.   A computational model for analyzing the airflow in the airways was developed and several simulations were performed.  To capture the anisotropy of the inhaled airflow in the upper airways, the Reynolds stress transport model of turbulence was used in these simulations.  The simulation results for the inhalation rates of 15, 30 and 60 lit/min that represent, respectively, resting, normal and active conditions of human, were obtained.Micro particles transport and deposition in the realistic model of human upper airways were studied.  Micro particles transport was analyzed using the Lagrangian particle trajectory approach.  Since the mass fraction of inhaled particles was very small, the one-way coupling assumption was used.  That is, the air flow carries the particles, but particles do not affect the airflow condition.The predicted deposition fractions of the particles of different sizes in the upper airways were compared with the available experimental data and good agreements were found.  Comparison of the results of the deposition fraction obtained from the realistic model with the earlier simulations of the idealized geometry of the airways showed certain differences especially in regional depositions. Therefore, it was concluded that the realistic geometry must be used for more accurate evaluation of micro particle deposition rate especially for local and regional deposition.