An idealized geometry that mimics average nasal spray deposition in adults: A computational study

This work describes the development of an idealized geometry that mimics average regional deposition of nasal sprays within realistic adult nasal geometries. Previous simulation results in seven realistic nasal airways (Kiaee et al. Int. J. Num. Methods Biomed. Eng. 34: e2968, 2018) were used to establish target values of regional deposition. Characteristic geometric features observed to be common to all the realistic nasal airway geometries studied were extracted and included in the idealized geometry. Additional geometric features and size scaling were explored, in order to enhance deposition in specific regions based on the results of simulations done in preliminary versions of the idealized geometry. In total, more than one hundred thousand simulation cases were conducted across a range of particle parameters and geometric shapes in order to reach the final idealized geometry presented herein. For droplet velocities of 0-20 m/s, droplet sizes of 5-40 μm and at an inhalation flow rate of 15 l/min, regional deposition in the final idealized geometry compares favourably with average deposition in each of the vestibule, valve, olfactory, turbinate, nasopharynx, and outlet regions in the realistic geometries. The proposed idealized nasal geometry has potential for use in the development and testing of nasal drug delivery systems, allowing researchers to estimate in vivo regional nasal deposition patterns using a simple benchtop test apparatus.