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Characteristics of pressure drop, mass flow distribution and flow asymmetry in three‐dimensional branching networks based on model human bronchial tree
ZAMM - Journal of Applied Mathematics and Mechanics ( IF 2.3 ) Pub Date : 2020-06-23 , DOI: 10.1002/zamm.201900022 Kaustav Pradhan 1 , Abhijit Guha 1 , Prodosh Kumar Halder 1
ZAMM - Journal of Applied Mathematics and Mechanics ( IF 2.3 ) Pub Date : 2020-06-23 , DOI: 10.1002/zamm.201900022 Kaustav Pradhan 1 , Abhijit Guha 1 , Prodosh Kumar Halder 1
Affiliation
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The complex flow field in the three‐dimensional internal passages of a model human bronchial tree is studied computationally. Up to five generations of branches, both in‐plane and out‐of‐plane configurations, two velocity profiles and varying inlet Reynolds number are considered. There exists substantial non‐uniformity of the fluid dynamic features (e.g. velocity field, pressure field, mass flow distribution or viscous dissipation) over any longitudinal plane or cross‐sectional plane of a particular branch as well as that between different branches of any generation. The flow asymmetry is explained here by attributing the fluid dynamics to three important features ‐ curvature of flow path, flow division at bifurcations and inertia of the flow. A synthesis of the present comprehensive study leads to the generalization that the out‐of‐plane configuration fosters greater degree of uniformity in the mass flow distributions in the various branches of any generation, but gives rise to greater flow non‐uniformity on any particular cross‐sectional plane as compared to the in‐plane configuration. The out‐of‐plane configuration also causes greater secondary flow and greater loss in total pressure in the network. The effectiveness of previously developed modular computational approaches is assessed through separate simulations for networks comprising two, three, four and five generations (containing 3, 7, 15 and 31 branches respectively). The inadequacy of Hagen‐Poiseuille type 1D model is demonstrated ‐ it can neither predict the flow asymmetry (captured by the 3D computations) nor determine the overall magnitude of loss in total pressure.
中文翻译：
基于人支气管树的三维分支网络中的压降，质量流量分布和流量不对称特征
通过计算研究了模型人支气管树的三维内部通道中的复杂流场。多达五代分支，包括平面内和平面外配置，两个速度曲线和变化的入口雷诺数。在特定分支的任何纵向平面或横截面上以及任何一代的不同分支之间的流体动力学特征（例如，速度场，压力场，质量流量分布或粘性耗散）都存在很大的不均匀性。这里通过将流体动力学归因于三个重要特征来解释流动不对称性：流动路径的曲率，分叉处的流动分配和流动的惯性。对当前全面研究的综合得出的结论是，平面外构造可促进任何一代的各个分支中质量流量分布的更大程度的均匀性，但会导致任何特定交叉处更大的流量不均匀性截面与平面内配置相比。平面外配置还会导致更大的二次流量和更大的网络总压力损失。通过对包含两代，三代，四代和五代（分别包含3、7、15和31个分支）的网络进行单独的仿真，可以评估先前开发的模块化计算方法的有效性。
更新日期：2020-06-23
中文翻译：
基于人支气管树的三维分支网络中的压降，质量流量分布和流量不对称特征
通过计算研究了模型人支气管树的三维内部通道中的复杂流场。多达五代分支，包括平面内和平面外配置，两个速度曲线和变化的入口雷诺数。在特定分支的任何纵向平面或横截面上以及任何一代的不同分支之间的流体动力学特征（例如，速度场，压力场，质量流量分布或粘性耗散）都存在很大的不均匀性。这里通过将流体动力学归因于三个重要特征来解释流动不对称性：流动路径的曲率，分叉处的流动分配和流动的惯性。对当前全面研究的综合得出的结论是，平面外构造可促进任何一代的各个分支中质量流量分布的更大程度的均匀性，但会导致任何特定交叉处更大的流量不均匀性截面与平面内配置相比。平面外配置还会导致更大的二次流量和更大的网络总压力损失。通过对包含两代，三代，四代和五代（分别包含3、7、15和31个分支）的网络进行单独的仿真，可以评估先前开发的模块化计算方法的有效性。
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