PIV Investigation of Oscillating Flows within a 3 D Lung Multiple Bifurcations Model
PIV Investigation of Oscillating Flows within a 3 D Lung Multiple Bifurcations Model
复制标题
3D 肺多分叉模型内振荡流的 PIV 研究
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
M. Riethmuller
中科院分区：
文献类型：
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作者：
A. Ramuzat;M. Riethmuller
细支气管炎和哮喘等呼吸道疾病的发病率有增加的趋势。这些疾病与空气污染和微粒污染物在肺部的沉积直接相关。为了预防或治疗这些疾病，大多数治疗方法都使用药物，这些药物以气雾剂的形式进入肺部。更好地了解人体肺脏内的气流机制有助于确定可能定义呼吸模式的因素。因此，研究正常或高呼吸频率下呼吸网络中的流动是理解颗粒传输和沉积的方法之一。本研究的目的是研究传导肺内的气流，以帮助更好地了解肺系统。本实验研究了连续三代肺分叉的三维模型内的振荡流动。实验测量采用了时间分辨粒子图像测速技术。该技术用于提供有关流动模式的动态和时间信息。通过在平均速度等于零的情况下施加振荡流速来进行实验，以了解和评估连续分叉中的流场。对于不同的雷诺数和沃姆斯利数，给出了连续分叉过程中速度随时间的变化规律。这项研究可以突出雷诺数和沃默尔西数对流动结构的影响，特别是对边界层发展的时间函数的影响。它还允许随着振荡频率的降低来研究流动的准稳态。此外，这项研究表明，在某些条件下，尽管存在强烈的二次运动，流动的结构可以从一个分叉重复到另一个分叉。最后，将稳定流动位移现象作为一种估算整个呼吸周期内颗粒输运的方法，说明了流体元件在整个周期内的位移。
The incidence of respiratory diseases such as bronchiole inflammation and asthma tends to increase. These diseases are directly linked to air pollution and to the deposition of particulate pollutants in the lungs. To prevent or treat these diseases, most therapies use drugs, which are delivered into the lungs in the form of aerosol. A better understanding of the airflow mechanism within the human pulmonary system could help to identify factors, which may define the respiratory patterns. Consequently, the investigation of flows in the respiratory network under normal or high breathing frequencies is one of the approaches used to understand particles transport and deposition. The aim of this study is to investigate airflow in the conductive pulmonary airways to contribute to a better understanding of the pulmonary system. This experimental study deals with the investigation of oscillatory flows within a 3D model of three successive generations of lung bifurcations. The experimental measurements are performed with the time-resolved Particle Image Velocimetry technique. This technique is used to provide dynamic and temporal information on the patterns of the flow. Experiments were performed by imposing oscillating flow rates around a mean velocity equal to zero in order to understand and assess the flow fields in successive bifurcations. The time-development of the velocity through successive bifurcations is presented for different Reynolds and Womersley numbers. This study allows to highlight the effects of both the Reynolds and Womerlsey numbers on the flow structure and in particular on the boundary layer development in function of time. It also allows to investigate the quasi-steadiness of the flow as the frequency of the oscillations decreases. Moreover, this investigation demonstrates that, in certain conditions, the structure of the flow can repeat itself from one bifurcation to the other one, despite the presence of strong secondary motions. Finally, the phenomenon of Steady Streaming Displacement, that concerns the displacement of a fluid element during a complete period, is illustrated as a way to estimate the particle transport during a complete breathing cycle.