Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstrasse 1, D-39108 Magdeburg, Germany.
J Colloid Interface Sci. 2010 Jun 1;346(1):32-6. doi: 10.1016/j.jcis.2010.02.015. Epub 2010 Feb 12.
Colloidal aggregates exposed to shear flow exhibit a size-dependent qualitative behavior [Becker et al. JCIS, 339, 362-372, 2009]. Under the same flow conditions small aggregates rotate like rigid bodies, whereas larger aggregates change their structure and even bigger aggregates break. In this study the transition from the rotational regime to the restructuring regime is investigated by DEM simulations. We applied a model for tangential interaction, capable of supporting bond-bending moments and torsional torques [Becker, Briesen, Phys. Rev. E, 78, 2008, 061404]. The probability for an aggregate to be affected by restructuring changes with the number of primary particle from zero to one in a small interval. The probability becomes a master curve being independent of the shear flow and the interparticle interactions if it is represented as a function of the relative deviation from the critical particles number, i.e. the number of primary particle where the probability of restructuring is equal to 0.5. Investigating the dependency of the critical particle number on the shear rates reveals power law relations which adequately represents the data. The exponents in the power law relations can particularly obtained from a fractal scaling argument.
胶体聚集体在剪切流中表现出尺寸相关的定性行为[Becker 等人，JCIS，339，362-372，2009]。在相同的流动条件下，小聚集体像刚体一样旋转，而较大的聚集体则改变其结构，甚至更大的聚集体会破裂。在这项研究中，通过 DEM 模拟研究了从旋转状态到重构状态的转变。我们应用了一种用于切向相互作用的模型，该模型能够支持键弯曲矩和扭转扭矩[Becker，Briesen，Phys. Rev. E，78，2008，061404]。聚集体受到重构影响的概率从零到一小段间隔内的一个单位逐渐增加。如果将其表示为相对偏离临界粒子数的函数（即重构概率等于 0.5 的初级粒子数），则该概率成为与剪切流和粒子间相互作用无关的主曲线。研究临界粒子数对剪切速率的依赖性揭示了能够充分代表数据的幂律关系。幂律关系中的指数可以特别从分形标度论点中获得。
