Sandnes B, Knudsen H A, Måløy K J, Flekkøy E G
Department of Physics, University of Oslo, PO Box 1048 Blindern, NO-0316 Oslo, Norway.
Phys Rev Lett. 2007 Jul 20;99(3):038001. doi: 10.1103/PhysRevLett.99.038001. Epub 2007 Jul 17.
A random, labyrinthine pattern emerges during slow drainage of a granular-fluid system in two-dimensional confinement. Compacted grains are pushed ahead of the fluid-air interface, which becomes unstable due to a competition between capillary forces and the frictional stress mobilized by grain-grain contact networks. We reproduce the pattern formation process in numerical simulations and present an analytical treatment that predicts the characteristic length scale of the labyrinth structure. The pattern length scale decreases with increasing volume fraction of grains in the system and increases with the system thickness.
在二维受限条件下，颗粒 - 流体系统缓慢排水过程中会出现一种随机的、迷宫状图案。压实的颗粒被推到流体 - 空气界面之前，由于毛细力与颗粒 - 颗粒接触网络所产生的摩擦应力之间的竞争，该界面变得不稳定。我们在数值模拟中再现了图案形成过程，并给出了一种解析处理方法，该方法预测了迷宫结构的特征长度尺度。图案长度尺度随着系统中颗粒体积分数的增加而减小，并随着系统厚度的增加而增大。
