Vezirov Tarlan A, Klapp Sabine H L
Institut für Theoretische Physik, Hardenbergstr. 36, Technische Universität Berlin, D-10623 Berlin, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Nov;88(5):052307. doi: 10.1103/PhysRevE.88.052307. Epub 2013 Nov 11.
Using Brownian dynamics (BD) simulations we investigate the impact of shear flow on structural and dynamical properties of a system of charged colloids confined to a narrow slit pore. Our model consists of spherical microions interacting through a Derjaguin-Landau-Verwey-Overbeek (DLVO) and a soft-sphere potential. The DLVO parameters were chosen according to a system of moderately charged silica particles (with valence Z~35) in a solvent of low ionic strength. At the confinement conditions considered, the colloids form two well-pronounced layers. In the present study we investigate shear-induced transitions of the translational order and dynamics in the layers, including a discussion of the translational diffusion. In particular, we show that diffusion in the shear-melted state can be described by an analytical model involving a single shear-driven particle in a harmonic trap. We also explore the emergence of zigzag motion characterized by spatiotemporal oscillations of the particles in the layers in the vorticity direction. Similar behavior has been recently observed in experiments of much thicker colloidal films.
我们使用布朗动力学（BD）模拟，研究了剪切流对限制在窄缝孔隙中的带电胶体系统的结构和动力学性质的影响。我们的模型由通过德亚金-朗道-韦弗-奥弗贝克（DLVO）和软球势相互作用的球形微离子组成。DLVO参数是根据低离子强度溶剂中适度带电的二氧化硅颗粒（价态Z~35）系统选择的。在所考虑的限制条件下，胶体形成两个明显的层。在本研究中，我们研究了层中平移有序和动力学的剪切诱导转变，包括对平移扩散的讨论。特别是，我们表明，剪切熔化状态下的扩散可以用一个解析模型来描述，该模型涉及一个处于谐振陷阱中的单个剪切驱动粒子。我们还探讨了以层中粒子在涡度方向上的时空振荡为特征的锯齿形运动的出现。最近在更厚的胶体薄膜实验中也观察到了类似的行为。
