Dapp Wolf B, Müser Martin H
Forschungszentrum Jülich, John von Neumann Institut für Computing and Jülich Supercomputing Centre, 52425 Jülich, Germany.
Universität des Saarlandes, Lehrstuhl für Materialsimulation, Saarbrücken, Germany.
Sci Rep. 2016 Feb 3;6:19513. doi: 10.1038/srep19513.
Percolation is a concept widely used in many fields of research and refers to the propagation of substances through porous media (e.g., coffee filtering), or the behaviour of complex networks (e.g., spreading of diseases). Percolation theory asserts that most percolative processes are universal, that is, the emergent powerlaws only depend on the general, statistical features of the macroscopic system, but not on specific details of the random realisation. In contrast, our computer simulations of the leakage through a seal--applying common assumptions of elasticity, contact mechanics, and fluid dynamics--show that the critical behaviour (how the flow ceases near the sealing point) solely depends on the microscopic details of the last constriction. It appears fundamentally impossible to accurately predict from statistical properties of the surfaces alone how strongly we have to tighten a water tap to make it stop dripping and also how it starts dripping once we loosen it again.
渗流是一个在许多研究领域广泛使用的概念，指物质通过多孔介质的传播（如咖啡过滤），或复杂网络的行为（如疾病传播）。渗流理论认为，大多数渗流过程具有普遍性，即出现的幂律仅取决于宏观系统的一般统计特征，而不取决于随机实现的具体细节。相比之下，我们通过密封处泄漏的计算机模拟——应用弹性、接触力学和流体动力学的常见假设——表明临界行为（流体在密封点附近如何停止流动）仅取决于最后一个缩窄处的微观细节。仅从表面的统计特性根本无法准确预测我们需要将水龙头拧紧到何种程度才能使其停止滴水，以及当我们再次拧松它时它又是如何开始滴水的。
