Numerical simulation of intranasal airflow in nasal numerical models with nasal septum perforations of different locations and sizes

Abstract

Objective: To investigate the effect of nasal septum perforation (SP) with different locations and sizes on nasal airflow by means of numerical simulation. Methods: Two healthy persons with normal nasal anatomy were enrolled in this study, including a 45 years old male (case 1) and a 36 years old female (case 2). Nasal CT data was used as the basis to create nasal airway numerical models of nasal SP with different locations (anterior caudal, central caudal, posterior caudal and anterior cranial) and sizes (diameter of 10 mm and 5 mm respectively). The inspiratory airflow characteristics (nasal cavity volume, nasal cavity wall area, pressure, nasal resistance, temperature, airflow velocity, wall shear stress, airflow-rate partitioning and vortex) of these nasal airway numerical models were simulated and analyzed. Pearson correlation analysis was performed between nasal resistances, airflow temperature and nasal cavity wall area. Results: In terms of pressure and nose resistance, the anterior caudal and larger size SP lead to more obvious variation of pressure distribution, and increased nasal resistance was especially found in the nasal cavity with anterior and medium caudal SP. In terms of temperature, the anterior (caudal and cranial) and larger size SP had significant effect on local temperature gradient as same as the anterior cranial and smaller size SP. Nasal heating efficiency was lower in nasal model with the anterior and larger size SP than that in the normal model. The temperature difference from the nostril to the end of nasal septum had positive correlation with nasal cavity wall area (R(2) value of case 1 and case 2 was 0.69, 0.41, respectively, all P<0.01). In terms of airflow velocity, the anterior caudal and cranial SP had more significant effect on the average airflow velocity in the nasal cavity. The anterior and medium caudal SP could make the airflow distribution in the asymmetric bilateral nasal cavity more unbalanced compared to the bilateral symmetrical nasal models. The anterior and medium SP resulted in a more pronounced vortex distribution than the posterior SP. Conclusions: The effect of SP on nasal cavity is related to its location and size. The anterior and larger size SP shows more negative influence on intranasal pressure, nasal resistance, heat transmission efficiency, airflow-rate partitioning than the posterior and smaller size SP.