Numerical analysis of stochastic dispersion of micro-particles in turbulent flows in a realistic model of human nasal/upper airway

•Micro-particle motion was investigated for turbulent flow in human upper airway.•The airway includes nasal cavity, nasopharynx, oropharynx, larynx and trachea.•The pattern of regional deposition is different between turbulent and laminar flows.•DRW model overestimates particle deposition in human nasal/upper airway.•CRW model can predict the particle turbulent dispersion in nasal/upper air way.

Turbulent flow field and particle deposition in a realistic model of human upper airway system including: nasal cavity, nasopharynx, oropharynx, larynx and trachea were analyzed numerically. The Lagrangian approach was used to find the trajectories of micron-size particles for the breathing rates of 30, 45 and 60 l/min. The continuous phase flow was evaluated using a RANS (Reynolds Average Navier-Stokes) turbulence model and the effect of turbulent fluctuations on particle trajectories was modeled using a continuous random walk (CRW) stochastic model, which is based on the normalized Langevin equation. The total and regional deposition fractions of micro-particles were evaluated and the effect of turbulent fluctuations on the particle deposition rate was investigated.