鼻腔气流运动的个体化测量

Computational fluid dynamics simulations of respiratory airflow in volunteers' nasal cavity

目的初步将鼻腔空气动力学应用于临床,数值模拟上呼吸道气流场,个体化测量气流运动参数。方法应用计算机断层扫描对10例正常鼻腔受试者进行鼻窦轴位扫描;同时测量鼻功能,得到鼻阻力值和鼻声反射曲线。将得到的上呼吸道连续断层图像顺序导入Mimics、Icem-cfd、Fluent、Cfd-post软件进行三维建模、有限元网格划分、瞬态计算、结果分析。从三方面验证数值模拟的合理性:①利用鼻声反射数据检验模型是否真实;②由鼻阻力仪得到气流速率值,设置数值模拟的瞬态边界条件;③用数值模拟得到的气流压力值计算鼻阻力,对比计算得到的鼻阻力值和实际测量得到的鼻阻力值。结果模型形态数据和鼻声反射数据有很好的吻合;数值模拟计算得到的鼻阻力值和实际测量鼻阻力值,2者比较差异无统计学意义。数值模拟可以得到呼吸周期中气体流场在整个上呼吸道的运动情况。结论所建模型可以真实反映鼻腔的实际解剖结构形态,数值模拟结果可靠,可以对上呼吸道气流进行个体化实时测量。

Objective To apply computational fluid dynamics simulations of respiratory airflow in clinical examination, and individually measure the airflow motion parameters. Methods Ten healthy noses with normal nasal structure and function were axially scanned by spiral CT, simultaneously all volunteers were examined by GM Rhinomanometer NR6 and GM Acoustic Rhinometry At. The continuous fault images of upper respiratory tract were imported into Mimics software for image seonentation and 3-dimensional models were obtained. Then model data were input to Ansys software to generate finite element mesh for transient computing and analysis. Rationality validation of workflow digital simulation was made from three aspects： ① using acoustic rhinometry results to test the simulation of model; ② setting transient boundary condition used airflow velocity value from Rhinomanometer results; ③ using air pressure value obtained from numerical simulation to calculate the nasal resistance value, then compared with the data from Rhinomanometer. Results The comparison indicates that the model and the numerical simulation were consistent. From the result we can observe the airflow distribution quantitatively in the nasal cavity in the period of respiration. Conclusion The model could truly reflect the actual anatomic structure and morphology of the nasal cavity, numerical simulation results were reliable. The airflow in the upper respiratory tract can be individualy measured.