Fachbereich Physik, Universität Konstanz, 78457, Constance, Germany.
Bosonit, AI Department, 26006, La Rioja, Spain.
Sci Rep. 2022 Jul 7;12(1):11525. doi: 10.1038/s41598-022-15577-w.
We experimentally and numerically study the flow of programmable active particles (APs) with tunable cohesion strength through geometric constrictions. Similar to purely repulsive granular systems, we observe an exponential distribution of burst sizes and power-law-distributed clogging durations. Upon increasing cohesion between APs, we find a rather abrupt transition from an arch-dominated clogging regime to a cohesion-dominated regime where droplets form at the aperture of the bottleneck. In the arch-dominated regime the flow-rate only weakly depends on the cohesion strength. This suggests that cohesion must not necessarily decrease the group's efficiency passing through geometric constrictions or pores. Such behavior is explained by "slippery" particle bonds which avoids the formation of a rigid particle network and thus prevents clogging. Overall, our results confirm the general applicability of the statistical framework of intermittent flow through bottlenecks developed for granular materials also in case of active microswimmers whose behavior is more complex than that of Brownian particles but which mimic the behavior of living systems.
我们通过实验和数值研究了可编程活性粒子（APs）在可调谐内聚力作用下通过几何约束的流动。与纯粹的排斥性颗粒系统相似，我们观察到突发尺寸呈指数分布，堵塞持续时间呈幂律分布。随着 APs 之间的内聚力增加，我们发现从拱主导的堵塞状态到凝聚力主导的状态发生了相当突然的转变，在这种状态下，液滴在瓶颈的孔径处形成。在拱主导的状态下，流速仅与凝聚力强度弱相关。这表明凝聚力不一定会降低颗粒通过几何约束或孔隙的效率。这种行为可以通过“光滑”的粒子键来解释，这种粒子键可以避免形成刚性的粒子网络，从而防止堵塞。总的来说，我们的结果证实了用于颗粒材料的间歇流动的统计框架在活性微泳者中的普遍适用性，尽管它们的行为比布朗粒子更复杂，但可以模拟生命系统的行为。
