The dynamics of confined extensional flows
The dynamics of confined extensional flows
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受限拉伸流的动力学
DOI：
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发表时间：
2016
影响因子：
3.7
通讯作者：
S. Pegler
中科院分区：
文献类型：
--
作者：
S. Pegler
我提出了一个理论和实验研究的浮动粘性流体膜引入到一个有限长度的通道，冰川冰架流动的动机。动态的特点是由粘性拉伸应力，横向剪切应力和驱动浮力的混合物。一个理论的基础上的宽度集成模型的开发和研究使用分析，渐近和数值方法。以恒定速率引入流体，发现流动接近稳态，具有取决于通道长度的两种可能的渐近形式。对于小于一半宽度的通道长度，流动类似于纯拉伸一维流动，其特征在于凹面轮廓，并且对通道出口（或产犊前缘）的位置不敏感。更大的长度导致更复杂的渐近结构，其中流动在短距离内向普遍无量纲形式的主流流动调整。与伸展状态完全相反，主流流由通道出口的位置控制。从一个新的实验室实验，涉及粒子测速的浮动液膜的数据比较以及预测沿通道速度。出于冰川学的应用，分析推广到幂律流变学和用于分类的流态的选择冰架的结果。对锋面速度的预测与地球物理资料吻合较好，表明该理论预测的普适剖面具有普遍性。
I present a theoretical and experimental study of floating viscous fluid films introduced into a channel of finite length, motivated by the flow of glacial ice shelves. The dynamics are characterized by a mixture of viscous extensional stresses, transverse shear stresses and a driving buoyancy force. A theory based on a width-integrated model is developed and investigated using analytical, asymptotic and numerical methods. With fluid introduced at a constant rate, the flow is found to approach a steady state with two possible asymptotic forms depending on the length of the channel. For channel lengths less than half the width, the flow is similar to a purely extensional one-dimensional flow, characterized by concave surface profiles and being insensitive to the position of the channel exit (or calving front). Greater lengths result in a more complex asymptotic structure in which the flow adjusts over a short distance towards a prevailing flow of universal dimensionless form. In complete contrast to the extensional regime, the prevailing flow is controlled by the position of the channel exit. Data from a new laboratory experiment involving particle velocimetry of a floating fluid film compares well with the predicted along-channel velocity. Motivated by glaciological application, the analysis is generalized to power-law rheologies and the results used to classify the flow regimes of a selection of ice shelves. The prediction for the frontal speed is in good agreement with geophysical data, indicating that the universal profile predicted by the theory is common in nature.
影响因子：
3.4
作者：
Griggs, J. A.;Bamber, J. L.
通讯作者：
Bamber, J. L.
影响因子：
5.2
作者：
Gudmundsson, G. H.;Krug, J.;Gagliardini, O.
通讯作者：
Gagliardini, O.