Université Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France.
Phys Rev Lett. 2021 Nov 19;127(21):218003. doi: 10.1103/PhysRevLett.127.218003.
We develop a constitutive model allowing for the description of the rheology of two-dimensional soft dense suspensions above jamming. Starting from a statistical description of the particle dynamics, we derive, using a set of approximations, a nonlinear tensorial evolution equation linking the deviatoric part of the stress tensor to the strain-rate and vorticity tensors. The coefficients appearing in this equation can be expressed in terms of the packing fraction and of particle-level parameters. This constitutive equation rooted in the microscopic dynamic qualitatively reproduces a number of salient features of the rheology of jammed soft suspensions, including the presence of yield stresses for the shear component of the stress and for the normal stress difference. More complex protocols like the relaxation after a preshear are also considered, showing a smaller stress after relaxation for a stronger preshear.
我们开发了一个本构模型，用于描述二维软密集悬浮液在达到堵塞状态之上的流变特性。从粒子动力学的统计描述出发，我们使用一系列近似方法，推导出了一个非线性张量演化方程，将偏应力张量的偏部分与应变速率张量和旋度张量联系起来。这个方程中的系数可以用堆积分数和粒子级参数来表示。这个本构方程源于微观动力学，定性地再现了堵塞软悬浮液流变学的许多显著特征，包括剪切应力和正应力差的屈服应力的存在。我们还考虑了更复杂的方案，如预剪切后的松弛，结果表明，预剪切越强，松弛后的应力就越小。
