  Spray atomization process involves complex multi-phase phenomena. Abundant
literature and validation of spray modelling for industrial applications like
fuel injection in internal combustion and turbine jet engines are available.
However, only a handful of studies, primarily limited to discrete phase
modelling, of low-pressure applications, such as nasal spray exists. This study
aims to provide insight into the external and near-nozzle spray
characterization of a continuous spray and establishes good validation against
the experiment. A 3-dimensional (3D) X-ray scanner was used to extract the
internal nasal spray nozzle geometry which was reconstructed to build a 3D
computational model. A novel volume-of-fluid to discrete phase transition model
(VOF-DPM) was used to track the liquid phase and its transition to droplets,
which was based on the shape and size of the liquid lumps. In this study, an
early pre-stable and stable phase of spray plume development was investigated.
Qualitative and quantitative analysis were carried out to validate the
computational model. A liquid column exited a nozzle which distorted at its
base with advancement in time and eventually formed a hollow-cone liquid sheet.
It then, disintegrated due to instability that produced fluctuations to form
ligaments resulting in secondary break-up. This study provides in-depth
understanding of liquid jet disintegration and droplet formation, which adds
value to future nasal spray device designs and techniques to facilitate more
effective targeted nasal drug delivery.
