Majumdar Sayantan, Sood A K
Department of Physics, Indian Institute of Science, Bangalore 560012, India and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA.
Department of Physics, Indian Institute of Science, Bangalore 560012, India.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Jun;89(6):062314. doi: 10.1103/PhysRevE.89.062314. Epub 2014 Jun 26.
The role of elastic Taylor-Couette flow instabilities in the dynamic nonlinear viscoelastic response of an entangled wormlike micellar fluid is studied by large-amplitude oscillatory shear (LAOS) rheology and in situ polarized light scattering over a wide range of strain and angular frequency values, both above and below the linear crossover point. Well inside the nonlinear regime, higher harmonic decomposition of the resulting stress signal reveals that the normalized third harmonic I_{3}/I_{1} shows a power-law behavior with strain amplitude. In addition, I_{3}/I_{1} and the elastic component of stress amplitude σ_{0}{E} show a very prominent maximum at the strain value where the number density (n_{v}) of the Taylor vortices is maximum. A subsequent increase in applied strain (γ) results in the distortions of the vortices and a concomitant decrease in n_{v}, accompanied by a sharp drop in I_{3} and σ_{0}{E}. The peak position of the spatial correlation function of the scattered intensity along the vorticity direction also captures the crossover. Lissajous plots indicate an intracycle strain hardening for the values of γ corresponding to the peak of I_{3}, similar to that observed for hard-sphere glasses.
通过大振幅振荡剪切（LAOS）流变学和原位偏振光散射，在高于和低于线性交叉点的宽应变和角频率值范围内，研究了弹性泰勒 - 库埃特流不稳定性在缠结蠕虫状胶束流体动态非线性粘弹性响应中的作用。在非线性区域内，所得应力信号的高次谐波分解表明，归一化三次谐波I₃/I₁随应变幅值呈现幂律行为。此外，I₃/I₁和应力幅值σ₀{E}的弹性分量在泰勒涡旋数密度（n₀）最大的应变值处出现非常显著的最大值。随后施加应变（γ）的增加会导致涡旋变形以及n₀随之降低，同时I₃和σ₀{E}急剧下降。沿涡度方向散射强度的空间相关函数的峰值位置也捕捉到了这种转变。李萨如图形表明，对于与I₃峰值对应的γ值，存在周期内应变硬化现象，这与硬球玻璃中观察到的情况类似。
