沙子里的图案

文章从物理学家的角度探讨颗粒体系中有序图案的产生和机理,探寻对广泛存在于自然界的非平衡态体系有序结构生成的理解.非平衡态体系的随机扩散与能量耗散的特性是有序结构生成的必备条件,所生成的图形则由这两个因素的权重比值和体系内部的对称性决定.具备以上因素,还需加上最后的一个决定性的关键因素,这就是熵的驱动.熵最大的态决定了体系是有序还是无序的排列.

Patterns in the sand

The formation of patterns and its underlining mechanism in granular systems are discussed from a physicist's point of view. These findings may help us understand the patterns formed in other more complex non-equilibrium systems. It is found that the randomization and dissipation properties of non-equilibrium systems are the underlining mechanisms for pattern formation. The symmetry of the system and the ratio of the weight factors of the above two mechanisms determine the pattern shapes. A final and key factor for pattern formation is the 2nd law of maximization of the entropy, which determines if a system is organized orderly or disorderly. Examples in granular systems are given to illustrate the above view points.