An asymptotic model of particle deposition at an airway bifurcation.
An asymptotic model of particle deposition at an airway bifurcation.
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气道分叉处颗粒沉积的渐近模型。
DOI：
10.1093/imammb/dqs002
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Grotberg,JamesB
中科院分区：
文献类型：
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作者：
Zierenberg,JenniferR;Halpern,David;Filoche,Marcel;Sapoval,Bernard;Grotberg,JamesB
研究了在吸气过程中，在气道分叉隆突处的颗粒输运和流动的模型，即与流过楔形体的气流相关的颗粒输运和沉积。利用匹配渐近性，得到了一个一致有效的解决方案，以代表高雷诺数的楔形体，考虑附近的楔形体和外部无粘区域的粘性边界层，然后用于解决粒子输运方程。有时，由于边界层的存在，防止了颗粒对楔形体的冲击。我们称之为边界层屏蔽（BLS）。这种效应可以分为不同的类型：排斥、捕获和偏转，它们由垂直于壁面的粒子初始负速度发生的变化来描述，要么改变符号，要么达到零，要么在边界层区域保持负值。沉积效率取决于临界斯托克斯数，但表现出弱依赖于雷诺数。在0 < Sc< 0.4的范围内，Scin的沉积效率在大雷诺数下产生以下关系，其中βπ是楔角。对于特定的沉积效率，Sc随着βπ的增加而减小。还计算了受影响颗粒的分布，并显示颗粒主要在隆突的一个气道直径内发生影响，这与计算流体动力学方法一致。这项工作提供了一个新的见解，BLS固有的楔形组件的结构是颗粒分布的主要原因。这一发现在将气溶胶沉积与气道疾病的位置以及治疗沉积的靶位点联系起来方面是重要的。
Particle transport and deposition associated with flow over a wedge is investigated as a model for particle transport and flow at the carina of an airway bifurcation during inspiration. Using matched asymptotics, a uniformly valid solution is obtained to represent the high Reynolds number flow over a wedge that considers the viscous boundary layer near the wedge and the outer inviscid region and is then used to solve the particle transport equations. Sometimes particle impaction on the wedge is prevented due to the boundary layer. We call this boundary layer shielding (BLS). This effect can be broken down into different types: rejection, trapping and deflection that are described by what happens to the particle's initial negative velocity normal to the wall either changing sign, reaching zero, or remaining negative in the boundary layer region. The deposition efficiency depends on the critical Stokes number but exhibits a weak dependence on Reynolds number. Deposition efficiency for Scin the range 0 < Sc< 0.4 yields the following relationship at large Reynolds numbers, where βπ is the wedge angle. For a specific deposition efficiency, Scdecreases as βπ increases. The distribution of impacted particles was also computed and revealed that particles primarily impact within one airway diameter of the carina, consistent with computational fluid dynamics approaches. This work provides a new insight that the BLS inherent to the wedge component of the structure is the dominant reason for the particle distribution. This finding is important in linking aerosol deposition to the location of airway disease as well as target sites for therapeutic deposition.