Experimental measurements and computational predictions of regional particle deposition in a sectional nasal model.

Knowledge of the regional deposition of inhaled particles in the nose is important for drug delivery and assessment of the toxicity of inhaled materials. In this study, computational fluid dynamics (CFD) predictions and experimental measurements in a nasal replica cast were used to study regional deposition of inhaled microparticles. The replica cast was sectioned into six regions of interest based on nasal anatomy: the nasal vestibule, nasal valve, anterior turbinates, olfactory region, turbinates, and nasopharynx. Monodisperse fluorescein particles with aerodynamic diameters of 2.6-14.3 μm were passed through the assembled cast in the presence of steady inspiratory airflow at 15 L/min. After each experiment, the cast was disassembled and the deposited fluorescein in each region was washed out and quantified with fluorescence spectrometry. A nasal CFD model was developed from the same magnetic resonance imaging scans that were used to construct the replica cast. Steady-state inspiratory airflow and particle deposition calculations were conducted in the CFD model using Fluent(™) at flow rates producing Stokes numbers comparable to experimental conditions. Total and regional particle deposition predictions from the CFD model were compared with experimental measurements from the replica cast. Overall, good agreement was observed between CFD predictions and experimental measurements with similar deposition trends in each region of interest. CFD predictions in central nasal regions demonstrated well-defined maximum values of 15%, 7%, and 12% in the anterior turbinates, olfactory, and turbinates regions, respectively, at particle sizes of 10-11 μm. These results demonstrate the use of a sectioned nasal CFD model based on anatomical regions of interest for nasal drug delivery to elucidate patterns of regional deposition within a human nasal cavity.