Kinematic irreversibility of oscillatory flow in expanding and contracting small airways
Kinematic irreversibility of oscillatory flow in expanding and contracting small airways
复制标题
小气道扩张和收缩时振荡流的运动学不可逆性
DOI：
10.1016/j.ijheatmasstransfer.2011.11.040
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发表时间：
2012
影响因子：
5.2
通讯作者：
Toshihiro Sera
中科院分区：
文献类型：
--
作者：
Gaku Tanaka;Masayoshi Ohgawara;Genri Inagaki;Makoto Hishida;Toshihiro Sera
对小气道扩张和收缩模型中的振荡流进行计算流体动力学（CFD）模拟，揭示了气道几何形状和节律性呼吸运动对振荡流运动学不可逆性的影响。利用 SPring-8 高分辨率同步辐射 CT 系统获得的小鼠 X 射线 CT 图像，重建了多分支小气道的 3D 真实模型。气道直径范围从初级分支的 360μm 到远端分支的 55μm。气道模型以正弦体积随时间变化的方式膨胀和收缩，使得几何形状在整个时期内保持自相似。使用Fluent软件包计算气道模型中的流体粒子轨迹。根据标记的微小颗粒在轴向方向上的方差来评价流体颗粒的分散性。结果表明，气道的扩张和收缩运动增强了轴向扩散。还发现稳定流的增强导致流体颗粒的分散增强。
Computational fluid dynamics (CFD) simulation was carried out for an oscillatory flow in an expanding and contracting model of small airways, and the effects of airway geometry and rhythmic breathing motion on the kinematic irreversibility of oscillatory flow were revealed. A 3D realistic model of multi-branching small airways was reconstructed from X-ray CT images of a mouse, which were obtained by the high-resolution synchrotron radiation CT system of SPring-8. Airway diameters range from 360μm in the primary branch to 55μm in the distal branch. The airway model was expanded and contracted in a sinusoidal volume change with time such that the geometry remains self-similar throughout a period. The Fluent software package was used for calculation of the fluid particle trajectory in the airway model. The dispersion of the fluid particle was evaluated in terms of the variance of the marked minute particles in the axial direction. The results show that the axial dispersion is enhanced by the expanding and contracting motion of the airways. It was also found that the augmentation of steady streaming is responsible for enhanced dispersion of fluid particles.