论文标题
一群绵羊群的流体动力学：边缘运动和远程相关性
Hydrodynamics of a dense flock of sheep: edge motion and long-range correlations
论文作者
论文摘要
绵羊是群体的动物，它们经常聚集成密集的，凝聚的羊群，尤其是在压力下。在本文中，我们使用图像处理工具来分析公开可用的空中视频，显示在牧羊犬的刺激下移动着密集的绵羊羊群。受运动的流动性的启发，我们实施了流体动力学方法，提取速度场，并测量它们在时空中的传播和相关性。我们发现，虽然羊群整体是静止的，但在边缘上发生了重要的动态，尤其是以波动的波动形式进行，像波浪一样，以及跨越整个羊群的大规模相关性。这些观察结果突出了合并界面动力学的重要性，例如以线张力的形式，当使用流体动力学框架来对密集，非极化群体的动力学进行建模。
Sheep are gregarious animals, and they often aggregate into dense, cohesive flocks, especially under stress. In this paper, we use image processing tools to analyze a publicly available aerial video showing a dense sheep flock moving under the stimulus of a shepherding dog. Inspired by the fluidity of the motion, we implement a hydrodynamics approach, extracting velocity fields, and measuring their propagation and correlations in space and time. We find that while the flock overall is stationary, significant dynamics happens at the edges, notably in the form of fluctuations propagating like waves, and large-scale correlations spanning the entire flock. These observations highlight the importance of incorporating interfacial dynamics, for instance in the form of line tension, when using a hydrodynamics framework to model the dynamics of dense, non-polarized swarms.
