Flow characteristics and particle deposition in multi-generation human lung airways

Abstract

In this thesis, the air flow and particle motion in lung model are numerically investigated using CFD technique. Firstly, the respiratory flow and particle motion in bifurcating airways with COPD (Chronic obstructive pulmonary diseases) was simulated. COPD always leads to local narrowing and obstruction of the airways. In order to understand the two-phase flow in such obstructed airways, four 3-D four-generation lung models based on the Weibel's model were considered. Computations were carried out in the Reynolds number range of 300~1200 and Stokes number range of 0.04~0.12, respectively. Flow patterns, particle motion and deposition efficiency were studied in detail. The results show that the obstruction has serious effect on the flow structure and particle deposition patterns in its downstream airways. Secondly, the inspiratory flow characteristics and the particle deposition in a CT-scanned human lung were numerically investigated. The five-generation airway was extracted from the trachea to segmental bronchi of a 60-year-old Chinese male patient. Computations were carried out in the Reynolds number range of 900~2100 and Stokes number range of 0.002~0.022. Flow field, particle deposition patterns, deposition efficiency and deposition factor were studied in detail. The air flow and particle motion of real lung model is quite different from that of symmetric model. In CT-scanned model, the flow pattern is very complex and the cartilage has significant influence on the particle deposition which would capture a lot of particles.