Abstract
In this paper, the effect of the turbulence and swirling of the inlet flow and the diameter of the nozzle on the flow characteristics and the particles' transport/deposition patterns in a realistic combination of the nasal cavity (NC) and the maxillary sinus (MS) were examined. A computational fluid dynamics (CFD) model was developed in ANSYS® Fluent using a hybrid Reynolds averaged Navier–Stokes–large-eddy simulation algorithm. For the validation of the CFD model, the pressure distribution in the NC was compared with the experimental data available in the literature. An Eulerian–Lagrangian approach was employed for the prediction of the particle trajectories using a discrete phase model. Different inlet flow conditions were investigated, with turbulence intensities of 0.15 and 0.3, and swirl numbers of 0.6 and 0.9 applied to the inlet flow at a flow rate of 7 L/min. Monodispersed particles with a diameter of 5 µm were released into the nostril for various nozzle diameters. The results demonstrate that the nasal valve plays a key role in nasal resistance, which damps the turbulence and swirl intensities of the inlet flow. Moreover, it was found that the effect of turbulence at the inlet of the NC on drug delivery to the MS is negligible. It was also demonstrated that increasing the flow swirl at the inlet and decreasing the nozzle diameter improves the total particle deposition more than threefold due to the generation of the centrifugal force, which acts on the particles in the nostril and vestibule. The results also suggest that the drug delivery efficiency to the MS can be increased by using a swirling flow with a moderate swirl number of 0.6. It was found that decreasing the nozzle diameter can increase drug delivery to the proximity of the ostium in the middle meatus by more than 45%, which subsequently increases the drug delivery to the MS. The results can help engineers design a nebulizer to improve the efficiency of drug delivery to the maxillary sinuses.
Highlights
The nasal cavity is an important organ in the human body with critical functions such as humidification and heating of inhaled air and filtration of pollutants from inhaled air (Drettner et al 1977; Keck et al 2000)
It can be observed from this Figure that the agreement between the results obtained in this study and the results reported in the
The main aim of the present study is to investigate the effect of inlet flow parameters and nozzle diameter at the inlet on the airflow behaviour and drug delivery to the maxillary sinus (MS)
Summary
The nasal cavity is an important organ in the human body with critical functions such as humidification and heating of inhaled air and filtration of pollutants from inhaled air (Drettner et al 1977; Keck et al 2000). The surface of the nasal cavity is mostly lined with mucosa. The mucosa is highly vascularized, such that the amount of blood flow to the surface of the NC is higher than that of blood flow to the brain (Mygind et al 1978). The mucosal surface of NC, which is highly vascularized, provides an attractive route for the treatment of sinus-related diseases, such as chronic rhinosinusitis (CRS) (Bell et al 2012; Rissler et al 2012; Wichers et al 2006). The locations of MS contribute to some of the challenges for achieving efficient drug delivery to those regions because most inhaled medications either deposit in the anterior region or pass through the inferior meatus and the main passage of the NC, which are far from the target site, the middle meatus and the MS (see Fig. 1b) (Bahadur et al 2012; Xi et al 2015)
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