气管支气管树内气流和颗粒运动的大涡模拟

LARGE EDDY SIMULATION OF AIRFLOW AND PARTICLE MOTION IN TRACHEOBRONCHIAL TREE

为更精确地描述真实人体呼吸道内的空气流动,明晰颗粒的运动沉积规律,本文从直接医学CT扫描得到的原始数据出发,利用图像辨识技术,重构了一个男性真人气管支气管树前三级的三维几何模型。采用大涡模拟的方法计算了非规则几何曲面结构内的气体流动现象,并在拉格朗日框架下跟踪颗粒的运动规律。数值计算得到了气流场的三维分布,以及颗粒的运动轨迹情况,结果表明现有基于Weibel的对称模型与真实人体的几何结构有较大的差异,而几何结构对流动影响较大;受非对称复杂结构影响,在不同截面的二次气流速度的分布规律不同;分叉后颗粒进入左右支气管的数量有明显的不同。

In order to describe airflow inside real human respiratory tract more accurately and elucidate principle of particle movement and deposition, a real three-dimensional geometry of human tracheobronchial tree representing first three generations was rebuilt by directly dealing with original CT （computer tomography） scanned respiratory tract images using image recognition technology. Large eddy simulation was used to describe the gas flow in the obtained complex geometry structure and the particles were traced in the Lagrangian frame. The three-dimensional distributions of airflow velocity and pressure, and trajectories of particles in the realistic geometry were computed and discussed. It indicates that the realistic CT-based geometry is very different from Weibel-based symmetrical model, and the calculated results are also different from that calculated by symmetrical model.