Numerical investigation of the flow field in the upper human airways

Abstract

The flow in a realistic model of the human lung is numerically simulated at steady and unsteady inspiration and expiration. A model of a human lung ranging from the trachea down to the sixth generation of the bronchial tree is used for the simulation. The numerical analysis is based on the Lattice-Boltzmann method, which is particularly suited for flows in extremely intricate geometries such as the upper human airways. The results for steady air flow at inspiration and expiration for a diameter based Reynolds number of ReD = 1250 evidence secondary vortex structures and air exchange mechanisms. It is shown that the asymmetric geometry of the human lung plays a significant role for the development of the flow field in the respiratory system. Secondary vortex structures observed in former studies are reproduced and described in detail. The solutions for unsteady respiration allow a detailed analysis of the temporal formation of secondary flow structures whereas the time dependence is much more pronounced at inspiration than at expiration. © 2009 WIT Press.