Institut für Theoretische Physik II, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
J Phys Condens Matter. 2011 Jul 20;23(28):284117. doi: 10.1088/0953-8984/23/28/284117. Epub 2011 Jun 27.
The collective dynamics in a binary mixture of colloidal particles which are driven in opposite directions by an external oscillatory field is examined by computer simulations in two spatial dimensions. Both Brownian dynamics (BD) computer simulations, which ignore solvent-mediated hydrodynamic interactions between the colloidal particles, and multi-particle collision dynamics (MPCD) simulations, which include hydrodynamic interactions, are employed. We first review recent results obtained by BD. Depending on the driving frequency and amplitude, lane formation parallel to the drive and band formation perpendicular to the drive occur. Band formation is stable only in a finite window of oscillation frequencies and driving strengths and is taken over by lane formation if the driving force is increased or the oscillation frequency is decreased. MPCD simulations, on the other hand, reveal that band formation is blurred by hydrodynamic interactions. During the front collisions of oppositely driven particles there is a strong vortical movement of the solvent which tends to mix particles and broaden the interface of the bands. This can either lead to a novel intermittent dynamical behaviour or to band rupture into local clusters. These effects, which are absent for BD, are characterized by the strengths of the enstrophy and its spectrum. We finally discuss possible experimental realizations of the models employed.
通过计算机模拟在二维空间中研究了由外部振荡场沿相反方向驱动的胶体粒子二元混合物中的集体动力学。布朗动力学（BD）计算机模拟忽略了胶体粒子之间溶剂介导的流体动力学相互作用，而多粒子碰撞动力学（MPCD）模拟则包括流体动力学相互作用。我们首先回顾了 BD 的最新结果。根据驱动频率和幅度，沿驱动方向形成车道，垂直于驱动方向形成带。带形成仅在有限的振荡频率和驱动强度窗口中稳定，如果驱动力增加或振荡频率降低，则被车道形成取代。另一方面，MPCD 模拟表明，流体动力学相互作用使带形成变得模糊。在相反驱动的粒子的前向碰撞中，溶剂会发生强烈的涡旋运动，这会导致粒子混合并扩大带的界面。这可能导致新的间歇动态行为或带破裂成局部簇。对于 BD 来说，这些不存在的影响可以通过旋度及其谱的强度来表征。最后，我们讨论了所采用模型的可能实验实现。
