Numerical investigation of unsteady particle deposition in a realistic human nasal cavity during inhalation

It is important to understand the patterns of two-phase flow in human nasal cavity in exploring the nasal pathology knowledge. In this paper, a realistic human nasal cavity geometry obtained from CT scans was applied to investigate the unsteady particle deposition during inhalation. The transient airflow pattern in the nasal cavity was investigated through imposing two sine wave curves at inlet with the tidal volume of 159 and 318 mL. The time-varying particle deposition pattern in the nasal cavity and a comparison of deposition characteristic between steady and unsteady inhalation were studied using the Lagrangian approach. By releasing particles continuously during inhalation, it was found that the highest transient deposition appeared about 1.4 s and the particle deposition at different time intervals was strongly depended on the instantaneous inlet flow rate. The total deposition of micro particles ranging from 1 to 20 mu m under unsteady inhalation was almost the same as that at steady state when the volume of inhaled airflow was equivalent. The deposition in the anterior region of the nasal cavity was overestimated at steady state for ignoring the gravity effects at the beginning and ending of unsteady inhalation. The results of this paper can be used for both toxicological and therapeutic applications.