Case Studies in the Human Respiratory System - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 284

Fig. 8.42 a Individual images of spray field in the near-nozzle region showing a swirling hollow
sheet of liquid. b Schematic of primary spray breakup

It is observed that the pressure induced by the nasal spray actuation causes the liquid
to emerge from the nozzle orifice under the action of both radial and axial forces. A
swirling thinning sheet of liquid is formed which becomes unstable, breaking up into
liquid ligaments before forming particles at a distance, called the break-up length,
from the nozzle.

8.4.2 Nasal Spray Atomization

A hollow spray cone is produced at the break-up length, with the majority of particles
located at the periphery of the hollow cone (Fig. 8.43 ). This type of atomization is
typical of pressure-swirl atomizers that are contained within the spray nozzle. The-
ories of pressure-swirl atomization has been studied extensively for the last century
with the vast majority of literature focused on high pressure applications, such as
fuel injectors found in the automotive industry; and the reader is referred to the