聚合物在有序多孔介质中驻点处的延伸主导了溶液流动增稠
Polymer extension at stagnation points governs flow thickening of polymer solutions in ordered porous media
AI总结：
通过建立模型和实验验证，发现有序多孔介质中流动增稠主要由驻点处聚合物延伸控制，而非无序介质中的非稳态流动波动。
摘要：
聚合物溶液在多孔介质中表现出异常的流动增稠——即宏观流动阻力突然增加——当流速超过阈值时，但在本体溶液中则不会。这一现象半个多世纪以来一直缺乏机理描述。这里，我们开发了一个模型，定量地将孔隙尺度流场和流体流变学与宏观流动增稠联系起来，并在二维和三维多孔介质的实验中进行了验证。我们发现，有序介质中的流动增稠由驻点处的聚合物延伸主导——与无序介质不同，在无序介质中，非稳态流动波动引起的粘性耗散也贡献显著。我们的结果为在能源、环境、工业和微流体应用中预测和控制此类流动提供了基础。
英文摘要：
Polymer solutions exhibit anomalous flow thickening -- marked by an abrupt increase in the macroscopic flow resistance -- above a threshold flow rate in a porous medium, but not in bulk solution. This phenomenon has evaded a mechanistic description for over half a century. Here, we develop a model that quantitatively links pore-scale flow fields and fluid rheology to macroscopic flow thickening, and validate it in experiments in two- and three-dimensional (2D and 3D) porous media. We find that flow thickening in ordered media is governed by polymer extension at stagnation points -- in contrast to disordered media, where viscous dissipation by unsteady flow fluctuations also contributes substantially. Our results provide a foundation to predict and control such flows in energy, environmental, industrial, and microfluidic applications.
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