Transition to Turbulence and Mixing in a Viscoelastic Fluid Flowing Inside a Channel with a Periodic Array of Cylindrical Obstacles
Transition to Turbulence and Mixing in a Viscoelastic Fluid Flowing Inside a Channel with a Periodic Array of Cylindrical Obstacles
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DOI：
10.1103/physrevlett.110.174501
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发表时间：
2013-04-22
影响因子：
8.6
通讯作者：
Ellero, Marco
中科院分区：
文献类型：
--
作者：
Grilli, Muzio;Vazquez-Quesada, Adolfo;Ellero, Marco
使用以 Oldroyd-B 本构方程为模型的粘弹性流体的拉格朗日模拟，我们证明了通过限制在通道中的紧密间隔的线性圆柱阵列的流动会在临界魏森伯格数 (We) 之上过渡到纯弹性湍流状态。高 We 状态的特征是不稳定运动和流动阻力突然增加，与实验观察结果定性一致。此外，还观察到积分量的幂律缩放行为以及质量的增强混合。基于动态模式分解方法的稳定性分析使我们能够识别导致不稳定行为的最具活力的模式，这些模式对应于由保持其形状的主流平流平流的聚合物过度或不足延伸的丝状结构。这些与时间相关的流动特征与最近数值模拟中报告的弹性波非常相似。 DOI：10.1103/PhysRevLett.110.174501
Using Lagrangian simulations of a viscoelastic fluid modeled with an Oldroyd-B constitutive equation, we demonstrate that the flow through a closely spaced linear array of cylinders confined in a channel undergoes a transition to a purely elastic turbulent regime above a critical Weissenberg number (We). The high-We regime is characterized by an unsteady motion and a sudden increase in the flow resistance in qualitative agreement with experimental observations. Furthermore, a power-law scaling behavior of the integral quantities as well as enhanced mixing of mass is observed. A stability analysis based on the dynamic mode decomposition method allows us to identify the most energetic modes responsible for the unsteady behavior, which correspond to filamental structures of polymer over- or underextension advected by the main flow preserving their shape. These time-dependent flow features strictly resemble the elastic waves reported in recent numerical simulations. DOI: 10.1103/PhysRevLett.110.174501