Phase transitions of fluids in shear flow
Phase transitions of fluids in shear flow
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DOI：
10.1088/0953-8984/9/29/001
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发表时间：
1997-07
期刊：
影响因子：
--
通讯作者：
A. Onuki
中科院分区：
文献类型：
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作者：
A. Onuki
我们回顾了相变流体中剪切效应的理论和实验。我们以近临界流体和聚合物溶液为代表，讨论聚合物共混物、凝胶和表面活性剂等体系中的相关问题。在近临界流体中，对流变形可以极大地改变临界行为、调幅节点分解和成核。在这种情况下，流体动力相互作用抑制了波动，并导致临界温度下移(剪切诱导混合)。对两相态的流变性和随机搅拌的影响进行了综述。另一方面，在共存曲线附近的半稀聚合物溶液中，粘弹性应力对组成波动有很大的影响。在剪切流中，这种动力耦合导致组成涨落的增强(剪切诱导的分离)。它们生长，但最终被对流变形破坏，产生混沌的动力学稳定状态，其中相分离不完全发生。利用基于粘弹性Ginzburg-Landau模型的计算机模拟研究了这种非线性剪切机制。
We review theories and experiments on the effects of shear in fluids undergoing phase transitions. We put emphasis on near-critical fluids and polymer solutions as representative examples, but also discuss related problems in polymer blends, gels, and surfactant systems, etc. In near-critical fluids, convective deformations can drastically alter the critical behaviour, spinodal decomposition, and nucleation. In this case the hydrodynamic interaction suppresses the fluctuations and gives rise to a downward shift of the critical temperature (shear-induced mixing). The rheology in two-phase states, and effects of random stirring are also reviewed. In semidilute polymer solutions near the coexistence curve, on the other hand, the composition fluctuations can be strongly influenced by the viscoelastic stress. In shear flow, this dynamical coupling results in enhancement of the composition fluctuations (shear-induced demixing). They grow, but are eventually disrupted by convective deformations, yielding chaotic dynamical steady states where phase separation is incompletely taking place. Such nonlinear shear regimes are examined using computer simulations based on a viscoelastic Ginzburg - Landau model.