NEAR WALL TURBULENCE EFFECTS ON PARTICLE TRANSPORT AND DEPOSITION IN HUMAN TRACHEOBRONCHIAL MULTI-LEVEL BIFURCATION MODEL

摘要

Transport and deposition of micro and nano-particles in the upper tracheobronchial tree were analyzed using a multi-level asymmetric lung bifurcation model. The multi-level lung model is flexible and computationally efficient by fusing sequence of individual bifurcations with proper boundary conditions. Trachea and the first two generations of the tracheobronchial airway were included in the analysis. In these regions, the airflow is in turbulent regime due to the disturbances induced by the laryngeal jet. Anisotropic Reynolds stress transport turbulence model (RSTM) was used for mean the flow simulation, together with the enhanced two-layer model boundary conditions. Particular attention is given to evaluate the importance of the "quadratic variation of the turbulent fluctuations perpendicular to the wall" on particle deposition in the upper tracheobroncial airways. In the past few decades, aerosol transport and deposition in human respiratory system has attracted the attention of many researchers in connection with better understanding of therapeutic drug delivery and pollutant related lung diseases. These earlier studies have identified the important factors affecting particle transport and deposition in the airways which are the airway structure, turbulence intensity, particle size, and density.