We investigate the collective dynamics of self-propelled droplets, confined in a one dimensional micro-fluidic channel. On one hand, neighboring droplets align and form large trains of droplets moving in the same direction. On the other hand, the droplets condensates, leaving large regions with very low density. A careful examination of the interactions between two “colliding” droplets demonstrates that takes place as a result of the interplay between and the absence of Galilean invariance. these observations, we propose a minimalistic 1D model of active particles and, combining analytical arguments and numerical evidences, we show that the model exhibits a transition to collective motion in 1D for a large range of values of the control parameters. Condensation takes place as a transient phenomena which tremendously slows down the dynamics, before the system eventually settles into a homogeneous aligned phase.

中文翻译：

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速度分散引起的对准：受游泳液滴实验启发的一维模型

我们研究了自驱液滴的集体动力学，将其限制在一维微流体通道中。一方面，相邻的液滴对齐并形成沿相同方向移动的大量液滴。另一方面，液滴凝结，留下大区域，密度非常低。仔细检查两个“碰撞”小滴之间的相互作用表明，这是由于伽利略不变性之间的相互作用和不存在而发生的。这些观察结果，我们提出了一个活性粒子的极简一维模型，并结合分析论证和数值证据，表明对于较大范围的控制参数值，该模型均表现出向一维运动的过渡。凝结是一种瞬态现象，会极大地减慢动力，