Simulation of sprayed particle deposition in a human nasal cavity including a nasal spray device

Effective nasal drug delivery is highly dependent on the delivery of drug from the nasal spray device. Atomisation of liquid spray occurs through the internal atomizer that can produce many forms of spray patterns and two of these, hollow-cone and full-cone sprays, are evaluated in this study to determine which spray pattern produced greater deposition in the middle regions of the nasal cavity. Past studies of spray particle deposition have ignored the device within the nasal cavity. Using computational fluid dynamics (CFD), two computational models of human nasal cavity model were reconstructed from CT-scans, where the difference between the two models was the presence of the nasal spray device accounting for the airway blockage at one of the nostrils. Experimental measurements from Particle Droplet Image Analyser (PDIA) were taken in order to gain confidence in determining the initial particle conditions for the computational models. An airflow field is induced through a negative pressure flow condition applied at the pharynx instead of constant flow rates at the left and the right nasal cavities. Subsequent airflow patterns and its effects on particle deposition, with and without a spray device, are compared. Contours and streamlines of the flow field revealed that the presence of a spray device in the nasal vestibule produced higher levels of disturbed flow, which helped the dispersion of the sprayed particles. Particle deposition was found to be high in the anterior regions of the nasal cavity caused by its inertia. Evaluation of the two spray types found that hollow spray cones produced more deposition in the middle regions of the nasal cavity. This paper also demonstrates the CFD methodology used, which can help in better understanding the design of future atomizers for nasal spray use.