论文标题
Lévy的步行和路径混乱在细长的结构的分布中移动到细胞涡流流动
Lévy Walks and Path Chaos in the Dispersal of Elongated Structures Moving across Cellular Vortical Flows
论文作者
论文摘要
在细胞涡流流中，即相反旋转的阵列，短而柔韧的细丝可以显示出简单的随机步行，通过其与流停滞点的伸展线圈相互作用。在这里，我们研究了半刚性丝的动力学，足以广泛采样涡度场。使用仿真，我们发现长期运输行为的各种多种多样的变化 - 随机步行，弹道运输和捕获 - 具体取决于细丝的相对长度和有效的灵活性。此外，我们发现细丝执行莱维步道，其扩散指数通常会随着灯丝长度的增加而降低，直到过渡到布朗尼步行。 Lyapunov指数同样随长度而增加。即使是完全刚性的细丝，其动力学是有限的，也会显示出令人惊讶的运输状态和混乱。快速细丝分散与``传送带''的潜在几何形状有关。在实验中使用反旋转辊的阵列发现了这些各种运输状态的证据，并浸入液体中并运输柔性色带。
In cellular vortical flows, namely arrays of counter-rotating vortices, short but flexible filaments can show simple random walks through their stretch-coil interactions with flow stagnation points. Here, we study the dynamics of semi-rigid filaments long enough to broadly sample the vortical field. Using simulation, we find a surprising variety of long-time transport behavior -- random walks, ballistic transport, and trapping -- depending upon the filament's relative length and effective flexibility. Moreover, we find that filaments execute Lévy walks whose diffusion exponents generally decrease with increasing filament length, until transitioning to Brownian walks. Lyapunov exponents likewise increase with length. Even completely rigid filaments, whose dynamics is finite-dimensional, show a surprising variety of transport states and chaos. Fast filament dispersal is related to an underlying geometry of ``conveyor belts''. Evidence for these various transport states are found in experiments using arrays of counter-rotating rollers, immersed in a fluid and transporting a flexible ribbon.
