发表机构
Faculdade de Física, Universidade Federal do Pará; MMML Lab, Department of Physics, University of Latvia; Departamento de Física, Universidade Federal do Ceará（帕拉联邦大学物理学院; 拉脱维亚大学物理系; 塞阿拉联邦大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过数值模拟揭示干性活性物质在圆形障碍物周围形成的涡旋存在两种标度行为：低密度下局域化饱和，高密度下质量广延增长并形成障碍物稳定的凝聚态。
AI 中文摘要
已知限制在刚性基底上的活性布朗粒子会聚集在刚性边界附近，并在适当条件下发生运动性诱导相分离（MIPS）。这种行为的一个特别引人注目的表现是在圆形障碍物周围形成自维持涡旋，这些涡旋充当粒子聚集的局部成核位点。尽管此类涡旋的若干动力学性质此前已被表征，但它们在热力学极限下的行为在很大程度上仍未得到探索。在此，我们研究了干性活性物质涡旋的质量和空间范围如何随系统尺寸标度。通过对与固定圆形障碍物相互作用的排斥性活性布朗粒子进行数值模拟，我们测量了涡旋质量、平均半径和最大半径作为全局面积分数、障碍物尺寸和系统尺寸的函数。我们发现了两个不同的标度区域。在低密度下，涡旋保持局域化，其特性随系统尺寸增大而趋于饱和。然而，在临界密度以上，涡旋质量随粒子总数呈广延性增长，而其空间尺寸则随系统尺寸线性标度，表明出现了由障碍物稳定的凝聚态。
英文摘要
Active Brownian particles confined to rigid substrates are known to accumulate near rigid boundaries and, under suitable conditions, undergo motility-induced phase separation (MIPS). A particularly intriguing manifestation of this behavior is the formation of self-sustained vortices around circular obstacles, which act as localized nucleation sites for particle aggregation. While several dynamical properties of such vortices have been previously characterized, their behavior in the thermodynamic limit remains largely unexplored. Here, we investigate how the mass and spatial extent of a dry active-matter vortex scale with system size. Using numerical simulations of repulsive active Brownian Particles interacting with a fixed circular obstacle, we measure the vortex mass, mean radius, and maximum radius as functions of the global area fraction, obstacle size, and system size. We find two distinct scaling regimes. At low densities, the vortex remains localized and its characteristic properties saturate as the system size increases. Above a critical density, however, the vortex mass grows extensively with the total number of particles, while its spatial dimensions scale linearly with the system size, indicating the emergence of an obstacle-stabilized condensed state.
Comments26 pages and 8 figures
