Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, 85747 Garching, Germany.
Phys Rev Lett. 2013 Apr 26;110(17):174501. doi: 10.1103/PhysRevLett.110.174501. Epub 2013 Apr 22.
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.
使用 Oldroyd-B 本构方程对黏弹性流体进行拉格朗日模拟，我们证明了在临界 Weissenberg 数 (We) 以上，通过通道中紧密排列的线性圆柱阵列的流动会过渡到纯弹性湍流状态。高 We 状态的特点是运动不稳定，流动阻力突然增加，这与实验观察结果定性一致。此外，还观察到积分量的幂律标度行为以及质量混合的增强。基于动态模态分解方法的稳定性分析使我们能够识别出负责非定常行为的最具能量的模式，这些模式对应于由主流输运的聚合物过度或欠伸展的丝状结构，同时保持其形状。这些时变流动特征与最近的数值模拟中报告的弹性波非常相似。
