CFD modelling of air and particle flows in different airway models

Abstract

Since complex structure of the human respiratory system leads to the profound effect of the air flow and particle deposition, a realistic and flexible airway model is crucial for predicting in vivo lung deposition of pharmaceutical aerosol. This work presented a CFD study of air and particle flows in a realistic parametrically controlled airway model developed by Kitaoka under different inspiratory conditions. The results were analysed with simulation data obtained in the classic Weibel airway (WA) model and compared with previous experimental and simulation studies. The comparison showed both difference and similarity between two models. The inspiratory airflow was symmetric in the WA model, whereas in the Kitaoka model non-symmetrical airflow was dominated throughout airways. The Kitaoka model, in comparison to the WA model, also showed more complicated particle deposition pattern with larger particle deposition efficiency. The flow rate, however, showed a similar effect to both models; i.e. generally particle deposition efficiency was higher as flowrate was higher. The Kitaoka model was then extended from 7 generations (KG7) to 11 generations (KG11) to study the effect of airway generation. The simulations showed little difference between two structures in terms of inspiratory air velocity and particle deposition efficiency. This suggests that the KG7 model is sufficiently structured to obtain realistic particle deposition pattern. The study demonstrates the Kitaoka model has a great potential in modelling lung deposition of particles under different conditions.