Numerical study of fibre deposition in a human nasal cavity

The inhalation of toxic particles such as asbestos fibres through the nasal airway has been found to cause harmful damage to the respiratory system. This study made use of CFD techniques to investigate deposition of fibrous particles in a human nasal cavity. A 3D computational model was created from CT scans which provided the framework to study the flow and deposition of fibres at a constant flow rate of 7.5 L/min. The effects of the fibres' elongated shape, density and size were incorporated into empirical drag correlations and the fibre trajectories were recorded through a Lagrangian tracking scheme. In general, good agreement was found in the right cavity and an overprediction in the left cavity. The major cause of deposition differences was in the geometrical variations between subjects as well as the left and right cavities. The dominant mechanism of deposition was by inertial impaction, with a majority of the particles depositing in the anterior region. It was found that asbestos had a very low deposition, ≈ 14 %, and was independent of fibre length. In comparison, the carbon fibre exhibited increases in deposition as the fibre length increased. A parameter ρ A_cross which represents the mass per unit length was used to equate the d_ae for different fibre lengths.