Self-Induced Polar Order of Active Brownian Particles in a Harmonic Trap
Self-Induced Polar Order of Active Brownian Particles in a Harmonic Trap
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DOI：
10.1103/physrevlett.112.238104
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发表时间：
2014-06-13
影响因子：
8.6
通讯作者：
Stark, Holger
中科院分区：
文献类型：
--
作者：
Hennes, Marc;Wolff, Katrin;Stark, Holger
外部谐波势中的流体动力学相互作用的活性粒子在足够大的佩克莱特数下形成自组装流体泵。在这里，我们给出了泵形成的定量标准，并表明颗粒方向在自感流场中对齐，与铁磁顺序令人惊讶地相似，其中活性佩克莱特数起着反温度的作用。粒子方向遵循类似于 exp(Ap(z)) 的玻尔兹曼分布 phi(p)，其中有序平均场 A 随活动佩克莱特数和极序参数缩放。粒子游动方向对齐的平均流场对应于强度与游动速度成正比的正则化斯托克斯莱特。将解析平均场结果与包含流体动力相互作用的布朗动力学模拟结果进行比较，发现可以很好地捕获自诱导对准。
Hydrodynamically interacting active particles in an external harmonic potential form a self-assembled fluid pump at large enough Peclet numbers. Here, we give a quantitative criterion for the formation of the pump and show that particle orientations align in the self-induced flow field in surprising analogy to ferromagnetic order where the active Peclet number plays the role of inverse temperature. The particle orientations follow a Boltzmann distribution phi(p) similar to exp(Ap(z)) where the ordering mean field A scales with the active Peclet number and polar order parameter. The mean flow field in which the particles' swimming directions align corresponds to a regularized Stokeslet with strength proportional to swimming speed. Analytic mean-field results are compared with results from Brownian dynamics simulations with hydrodynamic interactions included and are found to capture the self-induced alignment very well.