计算流体力学(CFD)模拟机械通气时下气道气流流场特性的方法及其可行性研究

目的 探索计算流体力学（computational fluid dynamics，CFD）技术模拟机械通气状态下呼吸系统内部气流流动的可行性，为CFD技术应用于机械通气的气流流场模拟奠定基础。方法 选取1名健康的中年男性志愿者进行头颈部加胸部MRI扫描，将获得的图像保存为DICOM格式导入Mimics17.0医学图像软件中构建气道三维模型，用Geomagic Studio 12软件进行网格划分后导入Ansys 14.5软件进行CFD模拟计算，对机械通气气道内部气流流场变化进行动态分析。结果 基于MRI图像数据构建气道三维模型，划分网格后对CFD模拟施加不同流速的入口边界条件，分析流速分布、壁压力分布、流场线变化情况以及局部管壁剪切应力的变化情况。结论 基于影像数据对气道进行三维重建，通过对模型进行CFD模拟发现，入口流速与气道内流体流速分布、壁剪切应力及壁压力均呈正相关，入口高流速易在气道分叉处形成涡流。

The study on the method and feasibility of computational fluid dynamics (CFD)to simulate the flow field characteristics of lower airway during mechanical ventilation

Objective To explore the feasibility of computational fluid dynamics (CFD) technology to simulate the flow of airflow inside the respiratory system under mechanical ventilation,and lay a foundation for the simulation of the flow field of CFD applied to mechanical ventilation. Methods A healthy middle-aged male volunteer was selected for head and neck and chest MRI scans. The obtained images were saved as DICOM format and imported into Mimics software to construct a three-dimensional airway model.The CFD simulation calculation was performed by ANSYS 14.5 software to dynamically analyze the flow field variation inside the mechanical ventilation airway. Results The airway 3D model was successfully constructed based on MRI image data. The inlet boundary conditions of different flow rates were applied to the CFD simulation.The flow velocity distribution, wall pressure distribution,flow field line variation and local wall shear stress were analyzed. Conclusion Based on medical imaging data,the airway was reconstructed in three dimensions.Through the CFD simulation of the model,it is found that the inlet flow velocity is positively correlated with the airway structure,wall pressure and wall shear stress.Turbulence can be observed at the bifurcation of airway when the inlet flow velocity is high.