For inhalation aerosols, it is well known that spray momentum and geometry characteristics can significantly influence deposition
in the mouth–throat (MT) region. However, little is knowabout the quantitative influence of spray momentum on aerosol transport and
deposition. The objective of this study was to evaluate the effect of spray momentum on deposition in a standard induction port (IP)
and a representative MT geometry using capillary-generated aerosols. Capillary aerosol generation (CAG) was selected as a model
spray aerosol system that has not been previously tested in a realistic throat geometry. To evaluate the effects of spray momentum,
the transport and deposition characteristics of transient capillary-generated aerosols were compared with ambient particles of the
same size inhaled at a steady flow rate of 30 L/min. To evaluate the influence of geometry, aerosols were considered in a standard
IP and a more realistic MT model. A previously tested CFD model was employed to simulate aerosol transport and deposition for
ambient and CAG spray aerosols in both the IP and MT geometries. Considering the capillary-generated spray, good agreement was
observed for the deposition of drug mass between the in vitro experiments (IP—15.3%, MT—19.4%) and CFD model predictions
without droplet evaporation (IP—14.7%, MT—20.8%). In all cases considered, deposition was increased for spray vs. ambient
aerosols and in the MT geometry vs. the IP model. Based on CFD results for a representative polydisperse aerosol distribution, the
deposition of ambient particles was highly sensitive to the geometry considered, with 2.9 times more deposition in the MT compared
to the IP model. In contrast, deposition was less influenced by the geometry for a CAG spray aerosol, with only a 25–40% deposition
increase in the MT. As a result, use of the simple IP model may provide a reasonable approximation of total MT deposition for
systems with high spray momentum. However, the IP model may be less useful for evaluating the total MT deposition in systems
with reduced spray momentum effects.