Characterization of Airflow Parameters in the Olfactory Fissure Zone Based on Fluid Mechanics Method

Airflow in the olfactory fissure region is a necessary condition for olfaction. However, due to the complex anatomy of the olfactory fissure, it is difficult to characterize the airflow in this region. At present, there are few studies on the airflow characteristics of the olfactory fissure. The aim of this study is to investigate the characteristics of objective indicators of airflow parameters in the olfactory fissure region, such as flow velocity, flow rate, pressure and flow ratio, from the perspective of biofluid mechanics. METHODS: In this study, the anatomical structure of the olfactory fissure zone was reconstructed in three dimensions using raw data from 32 healthy adults and 64 sinus computed tomography scans. To study the characteristics of airflow parameter variations in the olfactory fissure region in healthy adults, 10 cross-sectional sections were established in the olfactory fissure region using computational fluid dynamics after obtaining the airflow parameter values at different anatomical positions in the olfactory fissure region. RESULTS: The average flow rate of the ten cross-sections in the olfactory fissure zone was 19.22±9.74 mL/s, the average flow velocity was 0.51±0.21 m/s, the average flow percentage was 5.45%±2.52%, and the average pressure was −13.35±6.74 Pa. The percentile method was used to determine the range of reference values for P90: average flow rate of 0.02–35.87 mL/s, average flow velocity of 0.24–0.94 m/s, average flow percentage of 1.57%–9.93%, and average pressure of −30.4–4.42 Pa. Among the ten cross-sectional systems of the olfactory fissure, the median of Plane3N-Plane8N is more stable and representative. In the olfactory fissure system, the corresponding anatomical position of Plane3N-Plane8N was in the posterior region of the olfactory fissure, mainly at the junction of the anterior, middle 1/3 to the posterior middle turbinate, which was consistent with the main distribution area of the olfactory mucosa. CONCLUSION: This study shows that the application of computational fluid dynamic can rapidly achieve the characterization of airflow parameters in the olfactory fissure. The airflow through the olfactory fissure in healthy adults accounted for no more than 10% of the total flow volume of the nasal cavity. The airflow parameters in the anterior region of the olfactory fissure fluctuated significantly, while those flowing through the posterior region of the olfactory fissure were more stable. This could be due to the anterior section of the middle turbinate truncating the restriction of airflow into the olfactory fissure.