Flow patterns and deposition fraction of particles in the range of 0.1-10 μm at trachea and the first third generations under different breathing conditions

The velocity field and deposition fraction of the particles in the trachea and the first third generations of tracheobronchial tree are investigated with CFD simulation. The air flow rate of trachea is considered to be in the range of 15-60 l/min in accordance to four different activity levels of male adults. A physiologically realistic dichotomic airway bifurcation geometry with structured hexahedral meshes are constructed. The simulations with different hexahedral mesh densities have shown that the grid independent results will be reached with the average dimensionless distance of the first cell to the walls of y+≈0.5. The deposition fraction graph for particles in the range of 0.1-10 μm diameter has a minimum in the range of 0.1-1 μm particle diameter and after that it increases for larger particles. The results of the simulations under different breathing pattern have shown that deposition fraction significantly increases at higher Reynolds and Stokes numbers.