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Particle-Level Visualization of Hydrodynamic and Frictional Couplings in Dense Suspensions of Spherical Colloids
Physical Review X ( IF 12.5 ) Pub Date : 2021-06-14 , DOI: 10.1103/physrevx.11.021056
Taiki Yanagishima , Yanyan Liu , Hajime Tanaka , Roel P. A. Dullens

The rotational Brownian motion of colloidal spheres in dense suspensions reflects local hydrodynamics and contact forces, which are both key to nonlinear rheological phenomena such as shear-thickening and jamming, and transport in crowded environments, including intracellular migration and blood flow. To fully elucidate the role of rotational dynamics experimentally, it is crucial to measure the translational and rotational motion of all spheres simultaneously. Here, we directly access hydrodynamic and frictional coupling in colloidal suspensions up to arbitrarily high volume fractions using compositionally uniform colloidal spheres with an off-center, fully embedded core. We reveal interparticle hydrodynamic rotation-rotation coupling in charged colloidal crystals. We also find that higher local crystallinity in denser hard-sphere crystalline sediments enhances rotational diffusivity and that nearly arrested particles exhibit a stick-slip rotational motion due to frictional coupling. Our findings shed new light on the largely unexplored, local rotational dynamics of spherical particles in dense particulate materials.

中文翻译:

球形胶体稠密悬浮液中流体动力学和摩擦耦合的粒子级可视化

胶体球在稠密悬浮液中的旋转布朗运动反映了局部流体动力学和接触力,它们都是非线性流变现象(如剪切增稠和堵塞)以及在拥挤环境中运输(包括细胞内迁移和血流)的关键。为了通过实验充分阐明旋转动力学的作用,测量所有物体的平移和旋转运动至关重要。球体同时进行。在这里,我们使用具有偏心、完全嵌入核心的组成均匀的胶体球直接访问胶体悬浮液中的流体动力和摩擦耦合,直至任意高的体积分数。我们揭示了带电胶体晶体中的粒子间流体动力学旋转-旋转耦合。我们还发现密度较大的硬球结晶沉积物中较高的局部结晶度增强了旋转扩散率,并且由于摩擦耦合,几乎被捕获的颗粒表现出粘滑旋转运动。我们的发现为致密颗粒材料中球形颗粒在很大程度上未探索的局部旋转动力学提供了新的线索。
更新日期:2021-06-15
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