Mutual enhancements of CFD modeling and experimental data:: A case study of 1-μm particle deposition in a branching airway model
Mutual enhancements of CFD modeling and experimental data:: A case study of 1-μm particle deposition in a branching airway model
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DOI：
10.1080/08958370600748653
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发表时间：
2006-09-01
影响因子：
2.1
通讯作者：
Oldham, Michael J.
中科院分区：
文献类型：
--
作者：
Longest, P. Worth;Oldham, Michael J.
为了更好地了解气溶胶在呼吸道复杂流场中的动力学和沉积，体外实验和数值模拟技术被广泛采用。计算流体动力学（CFD）建模提供了轻松修改系统参数的灵活性，如流速、颗粒尺寸、系统几何形状和非均质出口条件。然而，一些数值误差和伪影可能导致非物理CFD结果。实验方法提供了物理现实主义的优势;然而，参数变化往往是困难的。本研究的目的是说明使用计算流体力学，以提高对实验结果的理解。同时，选定的实验结果已被用来部分验证计算流体动力学预测。一个特定的案例研究已被认为是集中在1 μ m的粒子沉积在生理上现实的分叉（PRB）模型的呼吸代3-5。该系统中的先前实验报告了约0.01%的沉积速率。已采用深入的CFD分析来评估经验模型的两种情况。第一种情况仅由PRB双分叉几何组成。第二种情况包括实验颗粒输送系统的一部分，其可能影响进入速度和颗粒分布。为了评估上游转捩和湍流的影响，已使用层流和低雷诺数k -ω近似对所考虑的两种情况进行了评估。结果表明，上游流的影响和湍流或过渡流起着重要的作用，在确定1 μ m的颗粒在模型中考虑的沉积。需要模拟上游流效应和层流，以匹配经验报告的沉积分数，并提供了两个数量级的改进，超过最初的计算流体动力学估计。这项研究强调了需要考虑实验粒子生成系统对进入呼吸模型的速度和粒子分布的影响。未来的工作是必要的，调查负责实验观察到的局部沉积模式的机制。
In order to better understand aerosol dynamics and deposition in the complex flow field of the respiratory tract, both in vitro experiments and numerical modeling techniques have widely been employed. Computational fluid dynamics (CFD) modeling offers the flexibility of easily modifying system parameters such as flow rates, particle sizes, system geometry, and heterogeneous outlet conditions. However, a number of numerical errors and artifacts can lead to nonphysical CFD results. Experimental methods offer the advantage of physical realism; however, parameter variation is often difficult. The objective of this study is to illustrate the use of CFD to enhance the understanding of experimental results. In parallel, the selected experimental results have been used to partially validate the CFD predictions. A specific case study has been considered focusing on 1-mu m particle depositions in a physiologically realistic bifurcation (PRB) model of respiratory generations 3-5. Previous experiments in this system report a deposition rate of approximately 0.01%. An in-depth CFD analysis has been employed to evaluate two cases of the empirical model. The first case consists of only the PRB double bifurcation geometry. The second case includes a portion of the experimental particle delivery system, which may influence the entering velocity and particle profiles. To assess the influence of upstream transition and turbulence, each of the two cases considered has been evaluated using laminar and low Reynolds number k -omega approximations. Results indicate that both upstream flow effects and turbulent or transitional flow play a significant role in determining the deposition of 1-mu m particles in the model considered. Simulating upstream flow effects and laminar flow was required to match the empirically reported deposition fraction and provided a two orders of magnitude improvement over initial CFD estimates. This study highlights the need to consider the effects of experimental particle generation systems on velocity and particle profiles entering respiratory models. Future work is necessary to investigate the mechanisms responsible for the experimentally observed local deposition patterns.