Analysis of air flow patterns in the human nose.

The nasal cavity is the main passage for air flow between the ambient atmosphere and the lungs. A preliminary requisite for any investigation of the mechanisms of each of its main physiological functions, such as filtration, air-conditioning and olfaction, is a basic knowledge of the air-flow pattern in this cavity. However, its complex three-dimensional structure and inaccessibility has traditionally prevented a detailed examination of internal in vivo or in vitro airflow patterns. To gain more insight into the flow pattern in inaccessible regions of the nasal cavity we have conducted a mathematical simulation of asymmetric airflow patterns through the nose. Development of a nose-like model, which resembles the complex structure of the nasal cavity, has allowed for a detailed analysis of various boundary conditions and structural parameters. The coronal and sagittal cross-sections of the cavity were modeled as trapezoids. The inferior and middle turbinates were represented by curved plates that emerge from the lateral walls. The airflow was considered to be incompressible, steady and laminar. Numerical computations show that the main air flux is along the cavity floor, while the turbinate structures direct the flow in an anterior-posterior direction. The presence of the turbinates and the trapezoidal shape of the cavity force more air flux towards the olfactory organs at the top of the cavity.