The transport and deposition of ellipsoidal fibers in human tracheobronchial airways

Elongated fibers are hazardous to human health due to the incapability of removing them from the respiratory system once inhaled. The high occurrence of bronchial carcinoma and lung cancer in certain occupational environment is linked to human exposure to these particles. Due to the anisotropy of fiber geometry, very limited work has been reported to study its dynamical behavior in human airway passages.;Part I of this research provides a comparative study of the accuracy of various turbulence models to predict particle transport and deposition in turbulent duct flows. The isotropic k-ϵ and anisotropic Reynolds stress transport models, as well as different turbulent boundary considerations are elaborated on. Part II presents the simulation of the transport and deposition of ellipsoidal fibers in low Reynolds number flow. The coupled translational and rotational motions are resolved numerically, and the fiber's dynamic behavior is analyzed. Part III performs numerical simulation of the transport and deposition of spherical particles in human tracheobronchial upper airways, where a multilevel human lung bifurcation model is proposed and used. Finally, the elongated fiber transport and deposition behavior is simulated in the human tracheobronchial airways by using the proposed bifurcation model, the flow model and the fiber transport model from earlier discussions.;This thesis studies the transport phenomena of ellipsoidal fibers within the human respiratory system. The objective is to develop an efficient computational model to analyze and predict the transport and deposition of inhaled particles in the human tracheobronchial airways. The dynamics of the ellipsoidal fiber in the human airways are given by the Lagrangian simulation along the fibers' trajectory. The motion of the fiber, and its relationships with the breathing rate, fiber size and shape, particle-to-fluid density ratio, and the local airway features are discussed.