AI 中文总结
该研究通过数值模拟探究二维对流卷中活性扬努斯粒子的运动诱导相分离，分析自推进、堆积分数与平流的相互作用，揭示平流抑制聚集、重入相等现象，表明对流卷可调控活性物质非平衡集体行为。
AI 中文摘要
我们数值研究了二维对流卷中活性粒子的运动诱导相分离。我们分析了局域堆积分数分布、密度涨落、相应的相图以及扩散率曲线，以表征自推进、全局堆积分数与平流强度之间的相互作用。在弱流区域，系统呈现出以双峰密度分布、缓慢衰减的密度涨落以及扩散率急剧降低为特征的相分离。增强平流通过促进粒子输运并减少捕获来抑制聚集，导致运动诱导相分离的临界自推进速度发生偏移，且旋节区缩小。除了弱流平流对聚集的直观抑制作用外，我们的结果还揭示了若干非平凡现象，包括重入相行为：极高的自推进会通过促进粒子从致密区域逃逸而阻碍运动诱导相分离。我们还观察到密度分布强烈依赖于卷的周期性。这些发现表明，对流卷为控制活性物质中的非平衡集体行为提供了一种有效手段。
英文摘要
We numerically study motility-induced phase separation of active particles in two-dimensional convection rolls. We analyse local packing-fraction distributions, density fluctuations, the corresponding phase diagrams, and diffusivity curves to characterise the interplay between self-propulsion, global packing fraction, and advection strength. In the weak-flow regime, the system exhibits phase separation characterised by bimodal density distributions, slowly decaying density fluctuations, and a sharp reduction in diffusivity. Increasing advection suppresses clustering by enhancing particle transport and reducing trapping, leading to a shift in the critical self-propulsion velocity for motility-induced phase separation and a shrinkage of the spinodal region. Beyond the intuitive suppression of clustering by weak-flow advection, our results reveal several non-trivial phenomena including a reentrant phase behaviour where extremely high self-propulsion hinders motility-induced phase separation by facilitating particle escape from dense regions. We also observe that the density distributions strongly depend on roll periodicity. These findings demonstrate that convection rolls provide an effective means to control non-equilibrium collective behaviour in active matter.
Journal refThe Journal of Physical Chemistry B, 2026
