Absorption of self-propelled particles into a dense porous medium
Absorption of self-propelled particles into a dense porous medium
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将自驱动颗粒吸收到致密多孔介质中
DOI：
10.1039/d1cp01234g
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发表时间：
2021
影响因子：
3.3
通讯作者：
Chen Kang
中科院分区：
文献类型：
--
作者：
Qian Bing-shuang;Tian Wen-de;Chen Kang
我们研究自驱动粒子被吸收到有限尺寸的致密多孔介质中，该介质由障碍物阵列模拟。我们发现，根据推进强度与障碍物形成的排斥屏障的竞争以及渗透和推进持久性的特征时间尺度之间的对比，吸收过程表现出三种不同类型的行为。在 I 型和 II 型行为中，推进强度不足以克服势垒，因此粒子通过势垒跳跃动力学在介质中传输。粒子向介质中心的初始渗透在现象学上类似于正常的缓慢扩散过程。但令人惊讶的是，在最初的渗透过程之后，由于长时间的推进持久性，在 I 型介质的介质中心形成并生长了一个集中的颗粒聚集核。这种异常的“成核”现象不会出现在推进持久性较低的II型中。当推进强度非常高（III型）时，颗粒在介质中平稳传输，因此最初的缓慢扩散过程消失，小颗粒簇形成并在介质中随机合并。我们的结果为复杂环境中活性物体的应用奠定了基础，并提出了多孔介质的可能用途，例如在活性物质的选择或分类中。
We study the absorption of self-propelled particles into a finite-size dense porous medium, which is mimicked by an obstacle array. We find that, depending on the competition of the propelling strength versus the repulsive barrier formed by obstacles and the contrast between the characteristic time scales of permeation and propelling persistence, the absorption process exhibits three distinct types of behavior. In Type I and II behavior, the propelling strength is not large enough to surmount the barrier, and hence particles transport in the medium by barrier-hopping dynamics. The initial permeation of particles toward the medium center is phenomenologically similar to a normal slow diffusion process. But, surprisingly, after the initial permeation process, a concentrated nucleus of particle aggregates forms and grows at the medium center in Type I, due to the long propelling persistence. Such an abnormal “nucleation” phenomenon does not appear in Type II, in which the propelling persistence is low. When the propelling strength is very high (Type III), particles transport smoothly in the medium, hence the initial slow diffusion process disappears and small particle clusters form and merge randomly in the medium. Our results provide a foundation for applications of active objects in a complex environment and also suggest the possible usage of a porous medium, for example, in the selection or sorting of active matter.