van Limbeek Michiel A J, Ramírez-Soto Olinka, Prosperetti Andrea, Lohse Detlef
University of Twente, Physics of Fluids, Drienerlolaan 5, P. O. Box 217, 7500AE Enschede, The Netherlands.
Soft Matter. 2021 Mar 21;17(11):3207-3215. doi: 10.1039/d0sm01570a. Epub 2021 Feb 24.
By sufficiently heating a solid, a sessile drop can be prevented from contacting the surface by floating on its own vapour. While certain aspects of the dynamics of this so-called Leidenfrost effect are understood, it is still unclear why a minimum temperature (the Leidenfrost temperature T) is required before the effect manifests itself, what properties affect this temperature, and what physical principles govern it. Here we investigate the dependence of the Leidenfrost temperature on the ambient conditions: first, by increasing (decreasing) the ambient pressure, we find an increase (decrease) in T. We propose a rescaling of the temperature which allows us to collapse the curves for various organic liquids and water onto a single master curve, which yields a powerful tool to predict T. Secondly, increasing the ambient temperature stabilizes meta-stable, levitating drops at increasingly lower temperatures below T. This observation reveals the importance of thermal Marangoni flow in describing the Leidenfrost effect accurately. Our results shed new light on the mechanisms playing a role in the Leidenfrost effect and may help to eventually predict the Leidenfrost temperature and achieve complete understanding of the phenomenon, however, many questions still remain open.
通过充分加热固体，可使固定液滴漂浮在自身蒸汽上，从而避免其与表面接触。虽然人们对这种所谓的莱顿弗罗斯特效应的动力学某些方面有所了解，但为何在该效应显现之前需要一个最低温度（莱顿弗罗斯特温度T）、哪些特性会影响此温度以及哪些物理原理支配它，仍不清楚。在此，我们研究莱顿弗罗斯特温度对环境条件的依赖性：首先，通过增加（降低）环境压力，我们发现T升高（降低）。我们提出一种温度重新标度方法，使我们能够将各种有机液体和水的曲线合并为一条单一的主曲线，这为预测T提供了一个有力工具。其次，提高环境温度能使亚稳态悬浮液滴在低于T的越来越低的温度下保持稳定。这一观察结果揭示了热马兰戈尼流在准确描述莱顿弗罗斯特效应中的重要性。我们的结果为莱顿弗罗斯特效应中起作用的机制提供了新的见解，可能有助于最终预测莱顿弗罗斯特温度并完全理解该现象，然而，许多问题仍然悬而未决。
