Confinement is known to have profound effects on the collective dynamics of many active systems. Here, we investigate a modeled active system in circular confinement consisting of biased active particles, where the direction of active force deviates a biased angle from the principle orientation of the anisotropic interaction. We find that such particles can spontaneously form a spiral vortex with two concentric and counter-rotating regions near the boundary. The emerged vortex can be measured by the vortex order parameter which shows nonmonotonic dependencies on both the biased angle and the strength of the anisotropic interaction. Our work can provide an understanding of such dynamic behaviors and enable different strategies for designing ordered collective behaviors.

中文翻译：

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受限偏置活性粒子的出现螺旋涡

众所周知，限制对许多活跃系统的集体动力学有着深远的影响。在这里，我们研究了由偏置活性粒子组成的圆形限制中的建模活性系统，其中主动力的方向偏离了各向异性相互作用的主要方向的偏置角。我们发现这样的粒子可以自发地形成一个螺旋涡旋，在边界附近有两个同心和反向旋转的区域。出现的涡可以通过涡阶参数来测量，该参数显示了对偏角和各向异性相互作用强度的非单调依赖性。我们的工作可以提供对这种动态行为的理解，并为设计有序的集体行为提供不同的策略。