Plati A, Puglisi A
Department of Physics, University of Rome Sapienza, Piazzale Aldo Moro 2, 00185 Rome, Italy.
Institute for Complex Systems-CNR, Piazzale Aldo Moro 2, 00185 Rome, Italy.
Phys Rev Lett. 2022 May 20;128(20):208001. doi: 10.1103/PhysRevLett.128.208001.
We simulate vertically shaken dense granular packings with horizontal periodic boundary conditions. A coordinated translating motion of the whole medium emerges when the horizontal symmetry is broken by disorder or defects in the packing and the shaking is weak enough to conserve the structure. We argue that such a drift originates in the interplay between structural symmetry breaking and frictional forces transmitted by the vibrating plate. A nonlinear ratchet model with stick slips reproduces many faces of the phenomenon. The collective motion discussed here underlies phenomena observed recently with vibrofluidized granular materials, such as persistent rotations and anomalous diffusion.
我们模拟了具有水平周期性边界条件的垂直振动致密颗粒堆积。当堆积中的无序或缺陷打破水平对称性且振动足够弱以保持结构时，整个介质会出现协调的平移运动。我们认为这种漂移源于结构对称性破坏与振动板传递的摩擦力之间的相互作用。一个具有粘滑现象的非线性棘轮模型再现了该现象的许多方面。这里讨论的集体运动是最近在振动流化颗粒材料中观察到的现象（如持续旋转和反常扩散）的基础。
