Singh Abhinendra, Saitoh Kuniyasu
Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Department of Physics, Faculty of Science, Kyoto Sangyo University, Kyoto 603-8555, Japan.
Soft Matter. 2023 Sep 13;19(35):6631-6640. doi: 10.1039/d3sm00510k.
Dense suspensions often exhibit a dramatic response to large external deformation. The recent body of work has related this behavior to transition from an unconstrained lubricated state to a constrained frictional state. Here, we use numerical simulations to study the flow behavior and shear-induced diffusion of frictional non-Brownian spheres in two dimensions under simple shear flow. We first show that both viscosity and diffusivity / of the particles increase under characteristic shear stress, which is associated with lubrication to frictional transition. Subsequently, we propose a one-to-one relationship between viscosity and diffusivity using the length scale associated with the size of collective motions (rigid clusters) of the particles. We demonstrate that and / are controlled by in two distinct flow regimes, in the frictionless and frictional states, where the one-to-one relationship is described as a crossover from / ∼ (frictionless) to (frictional). We also confirm that the proposed power laws are insensitive to the interparticle friction and system size.
浓稠悬浮液通常对大的外部变形表现出显著响应。最近的一系列研究工作已将这种行为与从无约束润滑状态到有约束摩擦状态的转变联系起来。在此，我们使用数值模拟来研究二维简单剪切流中摩擦性非布朗球体的流动行为和剪切诱导扩散。我们首先表明，在特征剪切应力作用下，颗粒的黏度和扩散率/均会增加，这与从润滑到摩擦的转变相关。随后，我们利用与颗粒集体运动（刚性团簇）大小相关的长度尺度，提出了黏度与扩散率之间的一一对应关系。我们证明，在两种不同的流动状态下，即无摩擦状态和摩擦状态，黏度和扩散率/由控制，其中一一对应关系被描述为从/ ∼ （无摩擦）到 （摩擦）的交叉。我们还证实，所提出的幂律对颗粒间摩擦力和系统尺寸不敏感。
