Computer Simulation of Particle Deposition in the Upper Tracheobronchial Tree

Abstract

A computational model for simulating particle dispersion and deposition in the human tracheobronchial tree is developed. The trachea and the main bronchi are modeled as a two-dimensional duct with two symmetric branches, and a branching angle of 45°. For high inspiratory flow rates, the occurrence of turbulence in the air is considered. Using the thermodynami-cally consistent rate-dependent anisotropic turbulence model, the mean velocity, as well as the root-mean-square fluctuation velocity fields in the airways are evaluated. The instantaneous turbulence fluctuating velocity is simulated as a continuous Gaussian random vector field. The Brownian motion is modeled as a white noise process. The Stokes drag, the Brownian and the Saffman forces are included in the particle equation of motion. Several digital simulations for particle transport and deposition in the upper tracheobronchial airways for different breathing conditions are performed. For particles in the size range of 0.01 to 20 nm, the corresponding deposition rates on various surfaces are evaluated. The net deposition rates are compared with the available experimental data and earlier digital simulations for bifurcating tubes.