NUMERICAL-SIMULATION OF AIR-FLOW IN THE HUMAN NASAL CAVITY

An anatomically correct finite element mesh of the right human nasal c avity was constructed from CAT scans of a healthy adult nose. The stea dy-state Navier-Stokes and continuity equations were solved numericall y to determine the laminar airflow patterns in the nasal cavity at qui et breathing flow rates. In the main nasal passages, the highest inspi ratory air speed occurred along the nasal floor (below the inferior tu rbinate), and a second lower peak occurred in the middle of the airway (between the inferior and middle turbinates and the septum). Nearly 3 0 percent of the inspired volumetric pow passed below the inferior tur binate and about 10 percent passed through the olfactory airway. Secon dary flows were induced by curvature and rapid changes in cross-sectio nal area of the airways, but the secondary velocities were small in co mparison with the axial velocity through most of the main nasal passag es. The pow patterns changed very little as total half-nasal flow rate varied between resting breathing rates of 125 m/s and 200 ml/s. Durin g expiration, the peaks in velocity were smaller than inspiration, and the flow was more uniform in the turbinate region. Inspiratory stream line patterns in the model were determined by introducing neutrally bu oyant point particles at various locations on the external naris plane , and tracking their path based on the computed flow field Only the st ream from the ventral tip of the naris reached the olfactory airway. T he numerically computed velocity field was compared with the experimen tally measured velocity field in a large scale (20X) physical model, w hich was built by scaling up from the same CAT scans. The numerical re sults showed good agreement with the experimental measurements at diff erent locations in the airways, and confirmed that at resting breathin g flow rates, airflow through the nasal cavity is laminar.