Investigation of particle penetration in a nasal maxillary ostium with optimised T-junction geometry and pulsatile flow.

Effective drug delivery to the maxillary sinus is often limited by the narrow and variable shape of the maxillary ostium. To better understand and predict how surgical changes affect drug transport, the ostium can be modelled as a simplified T-junction. The geometric configuration of these junctions plays a crucial role in managing particle flow; however, optimal design parameters remain under-explored. This paper addresses this gap, by simulating a range of radius of curvatures $R_{\text{c}}$ at the T-junction and oscillatory flows with pulsation frequencies of 0, 30, 45, 60 and 75 Hz to analyse their effects on particle penetration and distribution. The results revealed that an anterior $R_{\text{c}}$ enhanced particle outflow through the y-branch (perpendicular) outlet, while a posterior $R_{\text{c}}$ limited this outflow. Comparisons of pulsating frequencies further showed that a lower frequency improved penetration into the y-branch. Interestingly, applying both anterior and posterior $R_{\text{c}}$ did not yield better performance than an anterior $R_{\text{c}}$ alone. Furthermore, a constant flow rate where $f=0$ Hz promoted greater particle outflow through the y-branch in the T-junction model. However, a pulsating frequency of 30 Hz improved deposition in the nasal airway. The study underscores the potential of targeted geometric adjustments to optimise flow and deposition in the maxillary ostium, providing valuable insight into drug delivery strategies and inhalation toxicology.