Universal coherent structures of elastic turbulence in straight channel with viscoelastic fluid flow
Universal coherent structures of elastic turbulence in straight channel with viscoelastic fluid flow
复制标题
粘弹性流体直通道弹性湍流的通用相干结构
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
V. Steinberg
中科院分区：
文献类型：
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作者：
N. K. Jha;V. Steinberg
在本研究中，我们研究了在直的二维通道粘弹性流体流动的流动结构和弹性湍流的性质，并测试了早期的观察。我们发现了条纹和流向涡共存的弱不稳定相干结构（CS）的自组织循环过程，前者被Kelvin-Helmholtz不稳定性破坏，导致混沌结构。该序列周期性地重复自身，导致随机稳态。这种自持过程（SSP）非常类似于一个理论和实验研究的牛顿湍流在直槽流。意想不到的新成分是弹性波的观测，这发现是关键的CS和SSP生成的存在，由于能量泵从大到小的尺度之前急剧的幂律衰减的弹性湍流能谱。研究结果表明，在弹性流体和牛顿流体的线性稳定平面剪切流动中，CSs通过自组织循环（SSP）向湍流过渡的普遍性。
In the present study, we investigated flow structures and properties of elastic turbulence in straight 2D channel viscoelastic fluid flow and tested earlier observations. We discovered self-organized cycling process of weakly unstable coherent structures (CSs) of co-existing streaks and stream-wise vortices, with the former being destroyed by Kelvin-Helmholtz-like instability resulting in chaotic structures. The sequence periodically repeats itself leading to stochastically steady state. This self-sustained process (SSP) remarkably resembles one investigated theoretically and experimentally for Newtonian turbulence in straight channel flow. The unexpected new ingredient is the observation of elastic waves, which finds to be critical for existence of CSs and SSP generation due to energy pumping from large to smaller scales preceding sharp power-law decay in elastic turbulence energy spectrum. The reported finding suggests the universality of CSs in transition to turbulence via self-organized cycling (SSP) in linearly stable plane shear flows of both elastic and Newtonian fluids.