Departament de Física de la Matèria Condensada, Universitat de Barcelona, Barcelona 08028, Spain.
Institut de Nanociència i Nanotecnologia, Universitat de Barcelona (IN2UB), Barcelona 08028, Spain.
Phys Rev Lett. 2021 Nov 19;127(21):214501. doi: 10.1103/PhysRevLett.127.214501.
Hydrodynamic interactions between fluid-dispersed particles are ubiquitous in soft matter and biological systems and they give rise to intriguing collective phenomena. While it was reported that these interactions can facilitate force-driven particle motion over energetic barriers, here we show the opposite effect in a flow-driven system, i.e., that hydrodynamic interactions hinder transport across barriers. We demonstrate this result by combining experiments and theory. In the experiments, we drive colloidal particles using rotating optical traps, thus creating a vortex flow in the corotating reference frame. We observe a jamminglike decrease of particle currents with density for large barriers between traps. The theoretical model shows that this jamming arises from hydrodynamic interactions between the particles. The impact of hydrodynamic interactions is reversed compared to force-driven motion, suggesting that our findings are a generic feature of flow-driven transport.
流体分散颗粒之间的流体动力学相互作用在软物质和生物系统中无处不在，它们引发了有趣的集体现象。虽然有报道称这些相互作用可以促进粒子在能量障碍上的驱动力运动，但在这里我们在一个流动驱动系统中展示了相反的效果，即流体动力学相互作用阻碍了跨越障碍的输运。我们通过结合实验和理论来证明这一结果。在实验中，我们使用旋转光阱驱动胶体颗粒，从而在共旋转参考系中产生涡流。我们观察到，当陷阱之间的大障碍时，颗粒电流随密度呈类似堵塞的减小。理论模型表明，这种堵塞是由于颗粒之间的流体动力学相互作用引起的。与驱动力运动相比，流体动力学相互作用的影响是相反的，这表明我们的发现是流动驱动输运的一个普遍特征。
