Numerical study of nanoscale and microscale particle transport in realistic lung models with and without stenosis

Abstract

The transport and deposition (TD) of inhaled aerosol particles in airways of human lungs are important for therapeutically targeted drug delivery in respiratory tracts. The airflow and particle TD depend on various aspects, including breathing pattern, geometry of lungs, particle properties and deposition mechanisms. In this paper, a computational fluid dynamics (CFD) study is conducted to understand the flow behaviour and PD of both nanoparticles and microparticles (particle diameter = 5 nm, 100 nm, 500 nm, 1 μm, 5 μm and 10 μm) in airways of mouth–throat and tracheobronchial of a human lung under the effect of stenosis. The contribution of impaction and diffusion mechanisms to the TD of particles with different diameters in human lung models with and without stenosis are investigated through numerical simulations using ANSYS FLUENT solver. The study was conducted under two flow rates of 15 L/min and 60 L/min. The stenosis at the right primary bronchi reduces the airway sectional by 75%. It is found that the pressure drop of the stenosis model increases by 83% compared to the healthy model. Over 75% of 10 μm particles are deposited in the mouth–throat and tracheobronchial airways. As the particle size is decreased to 5 nm, less than 10% of the particles are deposited in the airways, allowing over 90% particles to enter deeper part of the lung. The results suggest that the particle deposition efficiency in airways of mouth–throat and tracheobronchial increases with increasing the flow rate as well as the particle diameter because of the inertia impaction mechanism. The contribution of the diffusion mechanism is significantly decreased with the increase of either particle size or flow rate. The predicted particle deposition patterns in the airway with stenosis model would be useful to optimise a patient's treatment for drug delivery in the stenosis airway.