Developing mucociliary clearance model for the numerical simulation of two-way coupling particulate flow inside the nasal cavity in the presence of deep breathing

Generally, it is essential to investigate mucociliary clearance as a defensive mechanism for drug delivery through the respiratory tract system. However, regarding the vicinity of micro-macro scales inside the respiratory system, typically, it has been neglected in numerical simulations. Hence, in the current research, a new boundary condition is developed to consider the effects of mucociliary clearance on deposited particles inside the nasal cavity. The two main components in developing the mucociliary clearance model are, namely, the cilia metachronal wave and walladjacent cell information. The cilia metachronal wave and wall-adjacent cell velocity generally determine the velocity and direction of the mucociliary clearance model, respectively. Therefore, the new boundary condition does not create an extra computational cost. Accordingly, all developing procedures are performed using the open-source toolbox (OpenFOAM 7). Herein, by applying the new boundary condition to the nasal wall, it is observed that each deposited particle is trapped and followed a different path alongside the nasal wall. Moreover, the initial deposition location of particles is changed up to 3% by means of the new implemented boundary condition based on the particle aerodynamic diameter. Based on the results, tracking of particles for 5 min indicated that 42% of deposited particles inside the nasal valve are transferred to the main airway. This means that drug absorption locations change with the consideration of the mucociliary clearance model. The results reveal that such a simplified strategy to account for mucociliary clearance can contribute to the prediction accuracy of the transport of sprayed therapeutic drug particles through the nasal cavity.