Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
J Chem Phys. 2013 Jun 21;138(23):234902. doi: 10.1063/1.4809989.
We study the nonlinear dynamics of spherical colloids under the influence of a pressure driven flow at vanishing Reynolds number. The colloids are confined between two parallel planar walls with a distance comparable to the particle diameter and they interact hydrodynamically via the solvent. We show that the bounded Poiseuille flow gives rise to new classes of trajectories resulting in cross-streamline migration. Two particles moving on these new trajectories exhibit either bound or unbound states. In the first case they oscillate on closed trajectories in the center-of-mass frame. In the second case, they exhibit cross-swapping trajectories in addition to swapping trajectories which were already observed in unbounded or bounded linear shear flow. The different classes of trajectories occur depending on the initial positions of the two particles and their size. We present state diagrams in the lateral positions, where we categorize the trajectories and color code the oscillation frequencies of the bound states. Finally we discuss how the results on the two-particle system help to understand the stability of particle trains composed of several particles.
我们研究了在雷诺数趋于零时压力驱动流作用下的球形胶体的非线性动力学。胶体被限制在两个平行的平面壁之间，其距离与颗粒直径相当，并且通过溶剂进行流体动力学相互作用。我们表明，有界泊肃叶流会产生新的轨迹类别，从而导致流线间的迁移。两个沿这些新轨迹运动的粒子表现出束缚或非束缚状态。在第一种情况下，它们在质心框架中沿封闭轨迹振荡。在第二种情况下，除了在无界或有界线性剪切流中已经观察到的交换轨迹之外，它们还表现出交叉交换轨迹。不同类别的轨迹取决于两个粒子的初始位置及其大小。我们在横向位置呈现状态图，在那里我们对轨迹进行分类，并对束缚态的振荡频率进行颜色编码。最后，我们讨论了关于双粒子系统的结果如何帮助理解由多个粒子组成的粒子链的稳定性。
