论文标题
运动梯度中活性颗粒的极化密度模式
Polarization-Density Patterns of Active Particles in Motility Gradients
论文作者
论文摘要
密度调制和粒子极化的共定位是活动梯度中运动活动物质的特征。因此，它可以发挥吸烟枪的作用，以检测内在的微观活性。 我们采用活跃的布朗尼粒子（ABP）模型来得出一个突然活动步骤附近的单个Janus型游泳者的密度和极化曲线的精确分析表达式，包括具有依赖方向的推进速度的情况。我们的结果与同伴论文[1]中呈现的热微观游泳器的测量数据非常吻合，并且可以用作更复杂应用的模板，例如，用于运动性诱导的相位分离或物理边界的研究。 我们的形式结果背后的基本物理是通过示意性的两种物种``运行式撞击''模型来牢固捕获和阐明的。
The co-localization of density modulations and particle polarization is a characteristic emergent feature of motile active matter in activity gradients. It can therefore play the role of a smoking gun for the mesoscale detection of intrinsic microscopic activity. We employ the active-Brownian-particle (ABP) model to derive precise analytical expressions for the density and polarization profiles of a single Janus-type swimmer in the vicinity of an abrupt activity step, including situations with an orientation-dependent propulsion speed. Our results agree well with measurement data for a hot microswimmer presented in the companion paper [1] and can serve as a template for more complex applications, e.g., to motility-induced phase separation or studies of physical boundaries. The essential physics behind our formal results is robustly captured and elucidated by a schematic two-species ``run-and-tumble'' model.
