Moukarzel Cristian Fernando, Peraza-Mues Gonzalo, Carvente Osvaldo
Departamento de Física Aplicada, CINVESTAV del IPN, 97310 Mérida, Yucatán, México.
Universidad Politécnica de Yucatán, Carretera Mérida-Tetiz. Km 4.5, Ucú, 97357 Yucatán, México.
Phys Rev Lett. 2020 Jul 10;125(2):028001. doi: 10.1103/PhysRevLett.125.028001.
It is shown that vibrated packings of frictional disks self-organize cooperatively onto a rotational-transport state where the long-time angular velocity ω[over ¯]_{i} of each disk i is nonzero. Steady rotation is mediated by the spontaneous breaking of local reflection symmetry, arising when the cages in which disks are constrained by their neighbors acquire quenched disorder at large packing densities. Experiments and numerical simulation of this unexpected phenomenon show excellent agreement with each other, revealing two rotational phases as a function of excitation intensity, respectively, the low-drive (LDR) and the moderate-drive (MDR) regimes. In the LDR, interdisk contacts are persistent and rotation happens due to frictional sliding. In the MDR, disks bounce against each other, still forming a solid phase. In the LDR, simple energy-dissipation arguments are provided, that support the observed dependence of the typical rotational velocity on excitation strength.
结果表明，摩擦盘的振动堆积会协同自组织到一种旋转传输状态，即每个盘i的长时间角速度ω[上划线]₁不为零。稳定旋转是由局部反射对称性的自发破缺介导的，当盘被其相邻盘约束在其中的笼在大堆积密度下获得淬火无序时就会出现这种情况。对这一意外现象的实验和数值模拟显示出彼此高度吻合，揭示了作为激发强度函数的两个旋转相，分别是低驱动（LDR）和中驱动（MDR） regime。在LDR中，盘间接触持续存在，旋转是由于摩擦滑动而发生的。在MDR中，盘相互碰撞，仍形成固相。在LDR中，提供了简单的能量耗散论据，支持了观察到的典型旋转速度对激发强度的依赖性。
