Numerical Simulation of Nasal Resistance Using Three-dimensional Models of the Nasal Cavity and Paranasal Sinus

Previously, we used a nasal cavity model to analyze the intranasal airflow dynamics and numerically calculate the nasal resistance value. In this study, We attempted clarify the parameters influencing nasal resistance by newly developed computer model.

The computer simulation model was developed from the structures of nasal airway tract adopted from 1.0-mm slice computed tomography (CT) obtained from the 2 of the healthy volunteers. (model 1: the one at 35-year-old man, model 2: 25-year-old man.) We have calculated the nasal resistance by computer simulation calculations of both model 1 and model 2. These calculated values were compared with the values obtained from the established method of rhinomanometry. For the simulation, Fluent 17.2® (ANSYS, American) was employed for f luid a nalysis u sing the continuity equation for 3D incompressible flow and the Navies-Stokes equation for the basic equations. Both models were laminar models. The SIMPLE calculation method using the finite volume method was employed here, and the quadratic precision upwind difference method was used to discretize the convection terms.

The measured (simulation) values in Model 1 were 0.69 (0.48), 1.10 (0.41), and 0.42 (0.22) Pa/cm³/s on the right, left, and both sides, whereas those in Model 2 were 0.72 (0.21), 0.32 (0.09), and 0.22 (0.06) Pa/cm³/s, respectively.

Our results suggest that nasal resistance is possibly affected by the length of the inferior turbinate and the cross-sectional area of the choana and nasopharynx. Further experiments using additional nasal cavity and paranasal sinus models are warranted.