Numerical Simulation Of Influence Of Change In Upper Respiratory Tract Structure On The Temperature Distribution In Nasal Cavity

Nasal cavity is the portal of human respiratory system that serves as the front of main breathing passage of human beings. Besides respiratory, it provides the functions to adjust the gas gross, warm, humidify, filter and clean effect as while. The direct inhalation of cool air could cause a strong stimulation in the lung. The warming function of the normal structure of nasal cavity could make the temperature of inhalational cold air close to alveolar conditions.The complex structure of the human nasal cavity plays an important role in the distribution of temperature field in that nasal cavity. Some upper respiratory diseases are closely related to the abnormal structure of nasal cavity. At present, surgical treatment is mainly method for upper respiratory diseases. Because of the complicated structure of nasal cavity and the difference of every patient's nasal cavity structure, it is difficult to determine the distribution of airflow field and temperature field in different parts of the internal nasal cavity. Therefore the reasonableness and effectiveness of surgical treatment depend on the patient's feelings. But the distribution of temperature field is very difficult to judge only by these feelings of patients.Based on CT medical images of volunteers, such as patients with nasal septum deviation and adenoid hypertrophy, the 3D finite element model of the upper airway was reconstructed by using the method of surface rendering. From the results of the numerical simulation, the airflow distribution and the temperature field in the whole cavity in the course of respiration can be obtained and analyzed.The results show that compared with normal subjects, the total air flow rate of patients with nasal septum deviation increased, the structure of nasal cavity is complicated and the warming function had little change. The exit temperature of the patients with adenoid hypertrophy is relatively high compared with the temperature of normal nasal structure. The apparent vortex and the disorder of airflow field appeared in the obstruction of the cross section area of nasopharynx. The simulation of partial resection of inferior turbinate based on normal numerical model shows that the wanning function of the whole nasal cavity decreased.Through the numerical simulation of temperature field on different anatomical structure of nasal cavity, the effect of structural abnormality of nasal cavity on warming function of nasal cavity, the diagnosis of diseases, the operation plan and the assessment of surgical treatment is displayed in quantity. And these results also can be taken as the reference to subsequent research.