Pan Zhongcheng, de Cagny Henri, Weber Bart, Bonn Daniel
Van der Waals-Zeeman Institute, IoP, Science Park 904, Amsterdam, Netherlands.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Sep;92(3):032202. doi: 10.1103/PhysRevE.92.032202. Epub 2015 Sep 14.
We study the rheological behavior of concentrated granular suspensions of simple spherical particles. Under controlled stress, the system exhibits an S-shaped flow curve (stress vs shear rate) with a negative slope in between the low-viscosity Newtonian regime and the shear thickened regime. Under controlled shear rate, a discontinuous transition between the two states is observed. Stress visualization experiments with a fluorescent probe suggest that friction is at the origin of shear thickening. Stress visualization shows that the stress in the system remains homogeneous (no shear banding) if a stress is imposed that is intermediate between the high- and low-stress branches. The S-shaped shear thickening is then due to the discontinuous formation of a frictional force network between particles upon increasing the stress.
我们研究了简单球形颗粒的浓颗粒悬浮液的流变行为。在控制应力下，该系统呈现出S形流动曲线（应力与剪切速率），在低粘度牛顿区和剪切增稠区之间具有负斜率。在控制剪切速率下，观察到两种状态之间的不连续转变。使用荧光探针的应力可视化实验表明，摩擦是剪切增稠的根源。应力可视化显示，如果施加的应力介于高应力和低应力分支之间，则系统中的应力保持均匀（无剪切带）。然后，S形剪切增稠是由于应力增加时颗粒之间摩擦阻力网络的不连续形成。
