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Pump efficacy in a two-dimensional, fluid–structure interaction model of a chain of contracting lymphangions
Biomechanics and Modeling in Mechanobiology ( IF 3.5 ) Pub Date : 2021-07-17 , DOI: 10.1007/s10237-021-01486-w
Hallie Elich 1 , Aaron Barrett 1 , Varun Shankar 2 , Aaron L Fogelson 1, 3
Affiliation  

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.



中文翻译:

收缩淋巴管链的二维流固耦合模型中的泵效

淋巴通过淋巴脉管系统的运输是将多余的间质液返回到循环系统的机制,它对于液体稳态至关重要。收集淋巴管构成淋巴脉管系统的重要部分,并被瓣膜分成称为淋巴管的收缩段。尽管它很重要,但收集血管中的淋巴运输尚不清楚。我们提出了一个计算模型来研究通过有瓣膜收缩淋巴管链的淋巴流动。我们使用 Navier-Stokes 方程来模拟流体流动,并使用浸没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度、收缩方式、循环平均流量 (CMFRs) 的不利轴向压差 (AAPD)。在该模型中,较长的淋巴管链通常会产生较大的 CMFR,并且与较短的链相比,它们无法在更高的 AAPD 下产生阳性 CMFR。同时收缩泵在几乎每个 AAPD 和每个链条长度上都会产生最大的 CMFR。由于收缩时间和阀门动力学,非同步泵产生的 CMFR 低于同步泵;随着 AAPD 的增加,差异会减小。阀门动力学随收缩方式而变化,并表现出滞后的打开和关闭行为。我们的模型提供了对收缩传播如何影响流速和通过淋巴管链的运输的见解。并且与较短的链相比,它们无法在更高的 AAPD 下产生正 CMFR。同时收缩泵在几乎每个 AAPD 和每个链条长度上都会产生最大的 CMFR。由于收缩时间和阀门动力学,非同步泵产生的 CMFR 低于同步泵;随着 AAPD 的增加,差异会减小。阀门动力学随收缩方式而变化,并表现出滞后的打开和关闭行为。我们的模型提供了对收缩传播如何影响流速和通过淋巴管链的运输的见解。并且与较短的链相比,它们无法在更高的 AAPD 下产生正 CMFR。同时收缩泵在几乎每个 AAPD 和每个链条长度上都会产生最大的 CMFR。由于收缩时间和阀门动力学,非同步泵产生的 CMFR 低于同步泵;随着 AAPD 的增加,差异会减小。阀门动力学随收缩方式而变化,并表现出滞后的打开和关闭行为。我们的模型提供了对收缩传播如何影响流速和通过淋巴管链的运输的见解。随着 AAPD 的增加,差异会减小。阀门动力学随收缩方式而变化,并表现出滞后的打开和关闭行为。我们的模型提供了对收缩传播如何影响流速和通过淋巴管链的运输的洞察力。随着 AAPD 的增加,差异会减小。阀门动力学随收缩方式而变化,并表现出滞后的打开和关闭行为。我们的模型提供了对收缩传播如何影响流速和通过淋巴管链的运输的见解。

更新日期:2021-07-18
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