Chantelot Pierre, Lohse Detlef
Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, MESA+ Institute, and J. M. Burgers Center for Fluid Dynamics, University of Twente, P.O. Box 217, 7500AE Enschede, Netherlands.
Max Planck Institute for Dynamics and Self-Organisation, Am Fassberg 17, 37077 Göttingen, Germany.
Phys Rev Lett. 2021 Sep 17;127(12):124502. doi: 10.1103/PhysRevLett.127.124502.
Volatile drops deposited on a hot solid can levitate on a cushion of their own vapor, without contacting the surface. We propose to understand the onset of this so-called Leidenfrost effect through an analogy to nonequilibrium systems exhibiting a directed percolation phase transition. When performing impacts on superheated solids, we observe a regime of spatiotemporal intermittency in which localized wet patches coexist with dry regions on the substrate. We report a critical surface temperature, which marks the upper bound of a large range of temperatures in which levitation and contact coexist. In this range, with decreasing temperature, the equilibrium wet fraction increases continuously from zero to one. Also, the statistical properties of the spatiotemporally intermittent regime are in agreement with that of the directed percolation universality class. This analogy allows us to redefine the Leidenfrost temperature and shed light on the physical mechanisms governing the transition to the Leidenfrost state.
沉积在热固体上的挥发性液滴能够在自身蒸汽的气垫上悬浮，而不与表面接触。我们建议通过类比表现出定向渗流相变的非平衡系统来理解这种所谓的莱顿弗罗斯特效应的起始。当对过热固体进行撞击时，我们观察到一种时空间歇性状态，其中局部湿润斑块与基底上的干燥区域共存。我们报告了一个临界表面温度，它标志着悬浮和接触共存的大范围温度的上限。在这个范围内，随着温度降低，平衡湿润分数从零连续增加到一。此外，时空间歇性状态的统计特性与定向渗流普适类的统计特性一致。这种类比使我们能够重新定义莱顿弗罗斯特温度，并阐明控制向莱顿弗罗斯特状态转变的物理机制。
