Numerical simulation of transient air flow and particle deposition in a lung and bronchus of a human respiratory system

Document Type : Research Article

Authors

1 Department of Mechanical Engineering, Faculty of Engineering, Shiraz Branch, Islamic Azad University, Shiraz, Iran

2 Mechanical Engineering Group, Pardis College, Isfahan University of Technology, Isfahan, Iran

Abstract

In the present study, the realistic model of the human trachea with five generations that are obtained from computed tomography scan images is considered. Due to the complexity of trachea and lung geometry, many researchers have used unrealistic simple models. Therefore in the present study realistic model with all geometrical details are considered as a computational model. The airflow behavior, particle transport and deposition in various conditions such as steady flow, transient flow, light breathing and heavy breathing condition for various micro particles diameters are investigated. Governing equations are solved and obtained results show that the flow patterns in the realistic model are much more complicated than those of symmetrical models. Also, the particle deposition pattern in the realistic condition is very different from that of the symmetrical model and the details of the trachea are very important and affect the deposition fractions in the small airways. Also, results show that the turbulent effect should be counted properly since the particle deposition in turbulent flow is 30 percent greater than the laminar flow and the dominant mechanism of micro particle deposition is impaction and increasing of particles diameter, particle density, and the airflow rate leads to an increase of particle deposition.

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