Leyva Sergi Granados, Stoop Ralph Lukas, Tierno Pietro, Pagonabarraga Ignacio
Departament de Física de la Matèria Condensada, Universitat de Barcelona, Av. Diagonal 647, 08028, Barcelona, Spain.
Soft Matter. 2020 Aug 14;16(30):6985-6992. doi: 10.1039/d0sm00904k. Epub 2020 Jul 16.
We combine experiments and numerical simulations to investigate the emergence of clogging in a system of interacting paramagnetic colloidal particles driven against a disordered landscape of larger obstacles. We consider a single aperture in a landscape of immobile silica particles which are irreversibly attached to the substrate. We use an external rotating magnetic field to generate a traveling wave potential which drives the magnetic particles against these obstacles at a constant and frequency tunable speed. Experimentally we find that the particles display an intermittent dynamics with power law distributions at high frequencies. We reproduce these results by using numerical simulations and show that clogging in our system arises at large frequency, when the particles desynchronize with the moving landscape. Further, we use the model to explore the hidden role of flexibility in the obstacle displacements and the effect of hydrodynamic interactions between the particles. We also consider numerically the situation of a straight wall and investigate the range of parameters where clogging emerges in such case. Our work provides a soft matter test-bed system to investigate the effect of clogging in driven microscale matter.
我们结合实验和数值模拟，来研究在一个由较大障碍物构成的无序景观中，相互作用的顺磁胶体粒子系统中堵塞现象的出现。我们考虑在固定于基底上的不可移动二氧化硅粒子构成的景观中的一个单孔。我们使用外部旋转磁场来产生一个行波势，该势以恒定且频率可调的速度驱动磁性粒子对抗这些障碍物。实验上，我们发现粒子在高频时呈现出具有幂律分布的间歇性动力学。我们通过数值模拟重现了这些结果，并表明在我们的系统中，当粒子与移动景观失步时，在高频下会出现堵塞现象。此外，我们使用该模型来探索障碍物位移中灵活性的隐藏作用以及粒子间流体动力学相互作用的影响。我们还从数值上考虑了直壁的情况，并研究了在这种情况下出现堵塞现象的参数范围。我们的工作提供了一个软物质试验台系统，以研究驱动微尺度物质中堵塞现象的影响。
