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.