涡流与湍涡在人体呼吸道内药物气溶胶的优先聚集与沉积中的作用
Roles of vortices and turbulent eddies in particle preferential concentration and deposition in the human respiratory tract
AI总结：
本研究通过构建高保真呼吸道模型，对比URANS与SBES框架，揭示涡流与湍涡对呼吸道内药物气溶胶优先聚集和沉积的影响，指出瞬态涡流与湍涡的数值解析是准确预测颗粒传输沉积的关键。
AI中文摘要：
药物气溶胶的精准靶向是吸入疗法有效性与安全性的关键。本研究聚焦于涡流与湍涡对人体呼吸道内药物气溶胶优先聚集及沉积的影响。通过从计算机断层扫描（CT）图像重建从鼻腔到各级支气管的高保真呼吸道几何结构，并赋予符合生理实际的瞬态呼吸模式，构建了采用剪切应力输运（SST）k-ω湍流模型的非稳态雷诺平均纳维-斯托克斯（URANS）框架，以及人体呼吸道的应力混合涡模拟（SBES）框架。除流场分析外，还采用沃罗诺伊图（Voronoi diagrams）和一组新定义的空间精度指标，对颗粒分布与局部预测偏差进行定量表征。频谱分析显示，SBES模拟充分恢复了显著的柯尔莫哥洛夫-5/3惯性尺度律。此类湍流运动引发明显的径向湍流扩散，在喉咽中平面形成分形维数D>1.2的更高颗粒团簇。空间精度指标揭示了URANS模型的关键双重缺陷：全局上过度模糊近壁沉积约20%，同时无法解析绝大多数高浓度“热点”（前5%的局部极值）。这些发现强调，瞬态涡流与湍涡的数值解析是准确预测人体呼吸道内颗粒传输与沉积不可或缺的前提条件。
英文摘要：
Precise targeting of pharmaceutical aerosols is critical to the efficacy and safety of inhaled therapies. This study focused on the influences of vortices and turbulent eddies on preferential concentration and deposition of pharmaceutical aerosols within the human respiratory tract. By reconstructing a high-fidelity respiratory tract geometry spanning the nasal cavity down to sequential bronchi from computed tomography (CT) images and assigning physiologically realistic transient breathing profiles, an unsteady Reynolds-averaged Navier-Stokes (URANS) framework using the shear stress transport (SST) k-w turbulence model and a stress-blended eddy simulation (SBES) framework of human respiratory tract were built. Beyond flow field analyses, Vorono diagrams and a set of newly-defined spatial accuracy metrics were adopted to quantitatively characterize particle distributions and localized prediction discrepancies. Spectral analysis revealed that the SBES simulations adequately recovered the prominent Kolmogorov -5/3 inertial scaling law. Such turbulent motion induces pronounced radial turbulent dispersion, forming particle clusters with higher cluster fractal dimensions D> 1.2 on the mid-plane of the laryngopharynx. Spatial accuracy metrics uncovered a critical dual deficiency of the URANS model: globally over-smears near-wall deposition by roughly 20%, simultaneously fails to resolve most high-concentration `hotspots' (the top 5% local extrema). These findings highlighted that the numerical resolution of transient vortices and turbulent eddies constitutes an indispensable prerequisite for accurately predicting of particle transport and deposition in the human respiratory tract.
