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首页> 外文期刊>International Journal of Heat and Mass Transfer >Global and local transport properties of steady and unsteady flow in a symmetrical bronchial tree
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Global and local transport properties of steady and unsteady flow in a symmetrical bronchial tree

机译：对称支气管树中稳定和不稳定流的全局和局部传输特性

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摘要

The branching structures and bifurcation flows in human lung are crucial factors for the functioning of the respiratory system. In this paper, both steady and unsteady flow in a symmetrical bronchial tree have been investigated, and the global and local transport properties are explored by fractal geometry and computational fluid dynamics method, respectively. Firstly, total flow properties for steady laminar flow and pulsatile flow in a fractal tree-like network are derived, and the global fluid dynamics behavior under volume constrain is discussed accordingly. And then, a mathematical model is developed for the steady and unsteady gas flow as well as gas-particle two-phase flow in a four-generation bifurcation in order to study the local transport characteristics of bronchial tree. The results indicate that the critical successive diameter ratio for the first few generations is below the prediction of Murray's law while small airways follow Murray's law. It has been also shown that the asymmetrical and non-uniform flow distribution can be realized through a symmetric branching structure with increased Reynolds number. The asymmetric ratio is found to be scaled with the Reynolds number as x ～ Re~(0.00124) in the steady respiratory condition. The effect of Reynolds number and respiratory frequency on the flow distribution and particle deposit efficiency are studied for different respiratory conditions, which show that the particle deposit efficiency can be increased with increased Stokes number. The present work is important for the morphology of the bronchial tree and understanding the physical mechanism of the bifurcation flow.
机译：人肺中的分支结构和分叉流是呼吸系统功能的关键因素。本文研究了对称支气管树中的稳态和非稳态流动，并分别通过分形几何和计算流体动力学方法探讨了整体和局部输运特性。首先，推导了分形树状网络中稳定层流和脉动流的总流动特性，并讨论了在体积约束下的整体流体动力学行为。然后，针对四代分支中的稳态和非稳态气流以及气固两相流，建立了数学模型，以研究支气管树的局部运输特性。结果表明，前几代的临界连续直径比低于默里定律的预测，而小型航空公司则遵循默里定律。还已经表明，可以通过具有增加的雷诺数的对称分支结构来实现不对称和不均匀的流量分布。发现在稳定的呼吸条件下，不对称比率与雷诺数成比例，为x〜Re〜（0.00124）。研究了不同呼吸条件下雷诺数和呼吸频率对流量分布和颗粒沉积效率的影响，结果表明，随着斯托克斯数的增加，颗粒沉积效率可以提高。目前的工作对于支气管树的形态学和理解分叉流的物理机制很重要。

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  • 来源
  • 作者

    Peng Xu; Agus P. Sasmito; Cuihong Li; Shuxia Qiu;

  • 作者单位

    College of Science, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, PR China,Department of Mining and Materials Engineering, McGill University, 3450 University Street, Montreal H3A 2A7, Canada;

    Department of Mining and Materials Engineering, McGill University, 3450 University Street, Montreal H3A 2A7, Canada;

    College of Science, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, PR China;

    College of Science, China Jiliang University, 258 Xueyuan Street, Hangzhou 310018, PR China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Bronchial tree; Tree-like network; Fractal; Transport; Multiphase flow;

    机译：支气管树树状网络;分形运输;多相流;

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