Shear stress dependence of force networks in 3D dense suspensions
Shear stress dependence of force networks in 3D dense suspensions
复制标题
DOI：
10.1039/d1sm00184a
复制
发表时间：
2021-07-15
期刊：
影响因子：
3.4
通讯作者：
Clark, Aurora E.
中科院分区：
文献类型：
--
作者：
Edens, Lance E.;Alvarado, Enrique G.;Clark, Aurora E.
使用润滑流离散元模拟，研究了表现出剪切变稀和变稠的3D致密悬浮液的几何组织和力网络，作为颗粒间吸引相互作用强度变化的函数。当这些系统在剪切变稀和剪切变稠区域过渡时，在局部或全球尺度上都不会发生显著的几何拓扑重排。与此相反，大量的重组平衡的吸引力，润滑，和接触力观察到有趣的行为网络的增长和竞争。与先前的工作一致，在剪切变稀区域中，吸引力是主导的，然而，随着剪切增稠区域的接近，润滑力增加。润滑力与吸引力相反，但是随着粘度在增加的剪切应力下继续增加，润滑力由也抵抗吸引力的接触力主导。在剪切增稠过程中，接触力是主要的相互作用，并且比它们在剪切变稀状态下的值高一个数量级。在高吸引相互作用强度下，即使在剪切变稀条件下也可以形成接触网络，然而在接触网络成为剪切增稠的驱动机制之前仍然需要高剪切应力。在剪切增稠过程中的接触力网络的分析通常表明，一个均匀的传播网络，迅速形成整个空域;然而，增长模式表现出的结构，这是显着依赖于颗粒间相互作用的强度，表明剪切增稠机制的微妙变化。
The geometric organization and force networks of 3D dense suspensions that exhibit both shear thinning and thickening have been examined as a function of varying strength of interparticle attractive interactions using lubrication flow discrete element simulations. Significant rearrangement of the geometric topology does not occur at either the local or global scale as these systems transition across the shear thinning and shear thickening regimes. In contrast, massive rearrangements in the balance of attractive, lubrication, and contact forces are observed with interesting behavior of network growth and competition. In agreement with prior work, in shear thinning regions the attractive force is dominant, however as the shear thickening region is approached there is growth of lubrication forces. Lubrication forces oppose the attraction forces, but as viscosity continues to increase under increasing shear stress, the lubrication forces are dominated by contact forces that also resist attraction. Contact forces are the dominant interactions during shear thickening and are an order of magnitude higher than their values in the shear-thinning regime. At high attractive interaction strength, contact networks can form even under shear thinning conditions, however high shear stress is still required before contact networks become the driving mechanism of shear thickening. Analysis of the contact force network during shear thickening generally indicates a uniformly spreading network that rapidly forms across empty domains; however the growth patterns exhibit structure that is significantly dependent upon the strength of interparticle interactions, indicating subtle variations in the mechanism of shear thickening.