Galanis Jennifer, Harries Daniel, Sackett Dan L, Losert Wolfgang, Nossal Ralph
NICHD, National Institutes of Health, Bethesda, Maryland 20892-0924, USA.
Phys Rev Lett. 2006 Jan 20;96(2):028002. doi: 10.1103/PhysRevLett.96.028002. Epub 2006 Jan 19.
Vertically vibrated rod-shaped granular materials confined to quasi-2D containers self-organize into distinct patterns. We find, consistent with theory and simulation, a density dependent isotropic-nematic transition. Along the walls, rods interact sterically to form a wetting layer. For high rod densities, complex patterns emerge as a result of competition between bulk and boundary alignment. A continuum elastic energy accounting for nematic distortion and local wall anchoring reproduces the structures seen experimentally.
垂直振动的棒状颗粒材料被限制在准二维容器中会自组织成不同的图案。我们发现，与理论和模拟结果一致，存在密度依赖的各向同性-向列相转变。沿着容器壁，棒状颗粒通过空间相互作用形成一个润湿层。对于高棒状颗粒密度，由于体相排列和边界排列之间的竞争，会出现复杂的图案。一个考虑向列相畸变和局部壁面锚定的连续弹性能量模型再现了实验中观察到的结构。
