School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
Department of Mechanical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran.
Med Biol Eng Comput. 2024 Oct;62(10):3025-3041. doi: 10.1007/s11517-024-03117-9. Epub 2024 May 17.
The impact of drug delivery and particulate matter exposure on the human respiratory tract is influenced by various anatomical and physiological factors, particularly the structure of the respiratory tract and its fluid dynamics. This study employs computational fluid dynamics (CFD) to investigate airflow in two 3D models of the human air conducting zone. The first model uses a combination of CT-scan images and geometrical data from human cadaver to extract the upper and central airways down to the ninth generation, while the second model develops the lung airways from the first Carina to the end of the ninth generation using Kitaoka's deterministic algorithm. The study examines the differences in geometrical characteristics, airflow rates, velocity, Reynolds number, and pressure drops of both models in the inhalation and exhalation phases for different lobes and generations of the airways. From trachea to the ninth generation, the average air flowrates and Reynolds numbers exponentially decay in both models during inhalation and exhalation. The steady drop is the case for the average air velocity in Kitaoka's model, while that experiences a maximum in the 3rd or 4th generation in the quasi-realistic model. Besides, it is shown that the flow field remains laminar in the upper and central airways up to the total flow rate of 15 l/min. The results of this work can contribute to the understanding of flow behavior in upper respiratory tract.
药物输送和颗粒物暴露对人体呼吸道的影响受多种解剖学和生理学因素的影响，特别是呼吸道的结构及其流体动力学。本研究采用计算流体动力学（CFD）方法研究了两个人体空气传导区的 3D 模型中的气流。第一个模型使用 CT 扫描图像和人体尸体的几何数据的组合，从气管到第九代提取上呼吸道和中央气道，而第二个模型使用 Kitaoka 的确定性算法从第一 Carina 到第九代气道的末端开发肺气道。该研究考察了两种模型在吸气和呼气阶段不同肺叶和气道代之间的几何特征、气流速率、速度、雷诺数和压降的差异。从气管到第九代，两种模型在吸气和呼气过程中，平均气流速率和雷诺数均呈指数衰减。在 Kitaoka 模型中，平均空气速度呈稳定下降，而在准现实模型中，在第 3 代或第 4 代达到最大值。此外，研究表明，在上呼吸道和中央气道中，流场在总流量为 15 l/min 之前保持层流。这项工作的结果有助于理解上呼吸道中的流动行为。
