A numerical simulation study of airway flow: Impact of bronchial stenosis

Obstructive lung diseases, marked by airway stenosis, are chronic and pose significant mortality risks. This study aims to analyze airflow patterns in obstructed bronchi, comparing them to healthy airways during tidal breathing to improve our comprehension of disease effects on respiratory function. The current studies mostly overlook the specific morphology of the patient's upper airway or the elastic deformation of the airway soft tissues, which results in the existing results not being sufficient to effectively guide surgical treatment. In this paper, a realistic model of bronchial stenosis was obtained by CT data from a 71-year-old female patient. Full consideration was given to the nonlinear elastic material properties of the tracheal wall cartilage and smooth muscle and the dynamic changes in intra-pulmonary pressure, which are significant factors affecting the airflow field within the airway. The dynamic mesh technology and the Fluid-Structure Interaction (FSI) method, in conjunction with Computational Fluid Dynamics (CFD), were employed to analyze the impact of bilateral bronchial stenosis on the airflow state and the nonlinear mechanical behavior of the airway wall under different respiratory intensities. The simulation results exposed the distribution pattern of key parameters, such as airflow velocity, pressure, wall shear stress, and turbulent kinetic energy, indicating that bronchial stenosis significantly influences the air-flow motion, resulting in increased pressure, wall shear stress, and deformation of the airway wall. The finding revealed that the maximum airflow velocity, pressure, and wall shear stress all occurred in the stenosis areas of the bronchi, while the maximum deformation occurred on the smooth muscle side of the middle part of the main trachea. Additionally, turbulence occurs near the main trachea and carina, potentially related to airflow separation and local geometric changes. These insights contribute to a deeper understanding of the effects of bronchial stenosis on airway airflow dynamics and provide a scientific basis for the determination of clinical treatment plans and the prediction of treatment outcomes.