人体上呼吸道气流结构与气溶胶沉积数值模拟

Numerical Simulation for Airflow Structure and Aerosol Deposition in Human Upper Respiratory

人体上呼吸道内气流运动会导致吸入气溶胶在其内不同部位的沉积,进而会引发各种呼吸道疾病。运用计算流体动力学(CFD)方法对人体上呼吸道内气流运动特性和气溶胶沉积进行了数值模拟,通过试验对数值模拟模型进行了验证。研究结果表明:气流通过咽部、气管和支气管分叉发生分离气流运动,气流在声门下游的气管和支气管内壁形成局部高速区。在下游支气管内壁区形成新的边界层,靠近支气管内壁速度较高,而速度最大值形成于支气管边界层的外缘。气管和支气管内的气流结构特点致使在气管和支气管内壁形成较高的剪应力分布,剪应力较高容易伤害到气管和支气管内壁粘膜。惯性碰撞对于微尺度气溶胶沉积而言是主要的沉积机制。而湍流扩散、二次气流运动和环流气流运动对气溶胶在人体呼吸道内沉积同样具有重要的影响。

The aerosol deposition caused by air movement inside human upper respiratory tract can lead to respiratory diseases. The CFD （Computational Fluid Dynamic） technology was used to investigate the air movement characteristic and aerosol deposition within the human upper respiratory tract. The simulation results were validated by the experimental results based on the aerosol deposition experiment. The results show that the phenomenon of airflow separation appears near the outer wall of the pharynx, the trachea and the divider. The high velocity zone is created near the inner wall of the trachea and the divider. A new boundary layer is generated at the inner wall of the downstream bifurcation with the high velocity near the inner wall of the trachea. The maximum velocity appears at the exterior of the boundary layer. The airflow structure in the trachea and the bifurcation result in the high shearing strength acting on the inner wall of the trachea and bifurcation, finally may lead to the inner wall injury. Inertial impaction is the main mechanism of deposition for micro aerosols. Turbulent dispersion, secondary flows and recirculation flows also influence aerosol deposition in the upper respiratory tract.