Stengele Philipp, Lüders Anton, Nielaba Peter
Statistical and Computational Physics, Department of Physics, University of Konstanz, 78464 Konstanz, Germany.
Phys Rev E. 2022 Jul;106(1-1):014603. doi: 10.1103/PhysRevE.106.014603.
We investigate the formation of cohesive groups and the collective diffusion of colloidal spherocylinders with a motility driven by a simple visual perception model. For this, we perform Brownian dynamics simulations without hydrodynamic interactions. The visual perception is based on sight cones attached to the spherocylinders and perception functions quantifying the visual stimuli. If the perception function of a particle reaches a predefined threshold, an active component is added to its motion. We find that, in addition to the opening angle of the cone of sight, the aspect ratio of the particles plays an important role for the formation of cohesive groups. If the elongation of the particles is increased, the maximum angle for which the rods organize themselves into such groups decreases distinctly. After a system forms a cohesive group, it performs a diffusive motion, which can be quantified by an effective diffusion coefficient. For increasing aspect ratios, the spatial expansion of the cohesive groups and the effective diffusion coefficient of the collective motion increase, while the number of active group members decreases. We also find that a larger particle number, a smaller propulsion velocity of the group members, and a smaller threshold for the visual stimulus increase the maximum opening angle for which cohesive groups form. Based on our results, we expect anisotropic particles to be of great relevance for the adjustability of visual perception-dependent motility.
我们用一个简单的视觉感知模型驱动的运动性来研究粘性团簇的形成以及胶体球柱体的集体扩散。为此，我们进行了无流体动力学相互作用的布朗动力学模拟。视觉感知基于附着在球柱体上的视锥以及量化视觉刺激的感知函数。如果一个粒子的感知函数达到预定义阈值，就会向其运动中添加一个活性成分。我们发现，除了视锥的开口角度外，粒子的纵横比对于粘性团簇的形成也起着重要作用。如果粒子的伸长增加，棒状粒子自行组织成此类团簇的最大角度会明显减小。在一个系统形成粘性团簇后，它会进行扩散运动，这可以通过一个有效扩散系数来量化。对于增加的纵横比，粘性团簇的空间扩展和集体运动的有效扩散系数增加，而活性团簇成员的数量减少。我们还发现，更大的粒子数量、更小的团簇成员推进速度以及更小的视觉刺激阈值会增加形成粘性团簇的最大开口角度。基于我们的结果，我们预计各向异性粒子对于依赖视觉感知的运动性的可调节性具有重要意义。
