Pump efficacy in a two-dimensional, fluid-structure interaction model of a chain of contracting lymphangions
Pump efficacy in a two-dimensional, fluid-structure interaction model of a chain of contracting lymphangions
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DOI：
10.1007/s10237-021-01486-w
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发表时间：
2021-07-17
影响因子：
3.5
通讯作者：
Fogelson, Aaron L.
中科院分区：
文献类型：
--
作者：
Elich, Hallie;Barrett, Aaron;Fogelson, Aaron L.
淋巴通过淋巴血管的运输是将多余的间质液返回循环系统的机制，它对液体稳态至关重要。集合淋巴管是淋巴脉管系统的重要组成部分，由瓣膜分成可收缩的部分，称为淋巴管。尽管它很重要，淋巴在收集血管中的运输还没有被很好地理解。我们提出了一个计算模型来研究淋巴流通过链阀，收缩淋巴管。我们使用Navier-Stokes方程来模拟流体流动，并使用浸入边界法来处理二维非轴对称模拟中的双向流固耦合。我们使用我们的模型来评估链长、收缩方式和不利轴向压差（AAPD）对循环平均流速（CMFRs）的影响。在该模型中，较长的淋巴管链通常产生更大的cmfr，并且在较高的aapd下它们不能产生阳性的cmfr。同时，收缩泵几乎在每个AAPD和每个链长度上都产生最大的cmfr。由于收缩时间和阀门动力学的影响，非同步泵比同步泵产生更低的CMFRs；这种差异随着AAPD的增加而减小。阀门动态随收缩方式的不同而变化，并表现出迟滞的启闭行为。我们的模型提供了关于收缩传播如何影响流速和通过淋巴管链的运输的见解。
The transport of lymph through the lymphatic vasculature is the mechanism for returning excess interstitial fluid to the circulatory system, and it is essential for fluid homeostasis. Collecting lymphatic vessels comprise a significant portion of the lymphatic vasculature and are divided by valves into contractile segments known as lymphangions. Despite its importance, lymphatic transport in collecting vessels is not well understood. We present a computational model to study lymph flow through chains of valved, contracting lymphangions. We used the Navier-Stokes equations to model the fluid flow and the immersed boundary method to handle the two-way, fluid-structure interaction in 2D, non-axisymmetric simulations. We used our model to evaluate the effects of chain length, contraction style, and adverse axial pressure difference (AAPD) on cycle-mean flow rates (CMFRs). In the model, longer lymphangion chains generally yield larger CMFRs, and they fail to generate positive CMFRs at higher AAPDs than shorter chains. Simultaneously contracting pumps generate the largest CMFRs at nearly every AAPD and for every chain length. Due to the contraction timing and valve dynamics, non-simultaneous pumps generate lower CMFRs than the simultaneous pumps; the discrepancy diminishes as the AAPD increases. Valve dynamics vary with the contraction style and exhibit hysteretic opening and closing behaviors. Our model provides insight into how contraction propagation affects flow rates and transport through a lymphangion chain.