In the Leidenfrost effect a small drop of fluid is levitated above a sufficiently hot surface, on a persistent vapor layer generated by evaporation from the drop. The vapor layer thermally insulates the drop from the surface leading to extraordinarily long drop lifetimes. The top-view shape of the levitated drops can exhibit persistent star-like vibrations. I extend recent work [Burton et al. PRL 2012] to study the bottom surface of the drop using interference-imaging. In this work I use a high-speed camera and automated image analysis to image, locate and classify the interference fringes. From the interference fringes I reconstruct the shape and height profile of the rim where the drop is closest to the surface. I measure the drop-size dependence of the planar vibrational mode frequencies, which agree well with previous work. I observe a distinct breathing mode in the average radius of the drop, the frequency of which scales differently with drop size than the other modes. This breathing mode can be tightly coupled to a vertical motion of the drop. I further observe a qualitative difference in the structure and dynamics of the vertical profile of the rim between large and small drops.
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机译:在莱顿弗罗斯特效应中,一小滴液滴悬浮在足够热的表面上方,在由液滴蒸发产生的持久蒸气层上。蒸气层使液滴与表面绝热,从而导致液滴寿命特别长。悬浮液滴的顶视图形状可以表现出持续的星形振动。我扩展了最近的工作[Burton等。 PRL 2012],使用干涉成像技术研究液滴的底部表面。在这项工作中,我使用高速相机和自动图像分析功能对干涉条纹进行成像,定位和分类。从干涉条纹中,我重构出液滴最靠近表面的边缘的形状和高度轮廓。我测量了平面振动模式频率的墨滴大小依赖性,这与以前的工作非常吻合。我在液滴的平均半径上观察到独特的呼吸模式,其频率随液滴大小的变化与其他模式不同。该呼吸模式可以与液滴的垂直运动紧密结合。我进一步观察到大滴和小滴之间轮辋垂直轮廓的结构和动力学在质上存在差异。
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