NUMERICAL ANALYSIS OF FLOW CHARACTERISTICS FOR THE NORMAL HUMAN UPPER AIRWAY

Abstract

Based on the data from the spiral Computerized Tomography (CT) images, three dimensional models consisting of the airway from nasal cavity, pharynx and trachea to triple bifurcation are built. Computational fluid dynamics (CFD) method is applied to study the respiratory air flow dynamics within the upper respiratory tract of human body. The influence of different respiratory routes on airway resistance and within the respiratory air flow characteristics is studied under the respiration of the nose and mouth. The influence of the different respiratory route on the characteristics of airflow and the airway resistance were studied at the work of nasal and oral. When only a small amount of air flow is inhaled and exhaled through the oral, the distribution law of airflow in the airways is similar to that of breathing process only through the nose. With the increase of mouth breathing air flow rate, the airway of the highest airflow velocity and the total pressure drop are reduced. Except for the nasal cavity, where the airway resistance was decreased, the airway resistance of other parts was increased with increasing mouth breathing. When the airflow exchanged with the outside world mainly through mouth, the distribution of airflow in the airways were obviously different, especially in the nose, mouth and throat, which brought the new allocation of the airway resistance and the great reduction of nasal resistance. The airway resistance mainly concentrated in the oral cavity and the following airway. The results of numerical simulation are useful for studying the pathogenesis and diagnosing the diseases related to the anatomical structure and function of upper airway.