Tiwari Ishant, Upadhye Swanith, Akella V S, Parmananda P
Department of Physics, Indian Institute of Technology-Bombay, Mumbai, Maharashtra-400076, India.
Department of Physics, Indian Institute of Technology, Jammu, Jagti Campus, Jammu & Kashmir, 181221, India.
Soft Matter. 2021 Mar 18;17(10):2865-2871. doi: 10.1039/d0sm01999b.
Avalanche dynamics in an ensemble of self-propelled camphor boats are studied. The self-propelled agents are camphor infused circular paper disks moving on the surface of water. The ensemble exhibits bursts of activity in the autonomous state triggered by stochastic fluctuations. This type of dynamics has been previously reported in a slightly different system (J. Phys. Soc. Jpn., 2015, 84, 034802). Fourier analysis of the autonomous ensemble's average speed reveals a unimodal spectrum, indicating the presence of a preferred time scale in the dynamics. We therefor, entrain such an ensemble by external forcing by using periodic air perturbations on the surface of the water. This forcing is able to replace the stochastic fluctuations which trigger a burst in the autonomous ensemble, thus entraining the system. Upon varying the periodic forcing frequency, an optimal frequency is revealed at which the quality of entrainment of the ensemble by the forcing is augmented. This optimal frequency is found to be in the vicinity of the Fourier spectrum peak of the autonomous ensemble's average speed. This indicates the existence of an underlying deterministic component in the apparent aperiodic bursts of motion of the autonomous ensemble of active particles. A qualitative reasoning for the observed phenomenon is presented.
研究了一组自行推进的樟脑船中的雪崩动力学。自行推进的主体是浸有樟脑的圆形纸片，它们在水面上移动。该集合在随机波动触发的自主状态下表现出活动爆发。这种动力学类型此前曾在一个稍有不同的系统中报道过（《日本物理学会杂志》，2015年，84卷，034802）。对自主集合平均速度的傅里叶分析揭示了一个单峰谱，表明动力学中存在一个优选的时间尺度。因此，我们通过对水面施加周期性空气扰动的外部强迫来使这样一个集合同步。这种强迫能够取代在自主集合中触发爆发的随机波动，从而使系统同步。在改变周期性强迫频率时，揭示了一个最佳频率，在该频率下强迫对集合的同步质量得到增强。发现这个最佳频率在自主集合平均速度的傅里叶谱峰值附近。这表明在活性粒子自主集合明显的非周期性运动爆发中存在一个潜在的确定性成分。给出了对观察到的现象的定性推理。
