报告题目：Drop floating on a thin liquid film

报 告 人：徐磊教授（香港中文大学）

报告时间：2016年8月31日（周三）下午15:00

报告地点：嘉定园区学术活动中心102房间

报告摘要：

The behaviors of a droplet gently falling on a smooth solid or liquid surface are quite similar -- it can bounce, oscillate and eventually make contact with substrate. However, we identify a unique long-time floating state only appearing on liquid surface. To clarify this fundamental difference between liquid and solid, we coat solid substrate with a very thin liquid film (one-hundredth of drop diameter) and recover the long-floating state. This state requires the air gap under droplet to have perfect symmetry, and thus only appears on accurately-leveled substrate. A minute tilting as small as 0.3 degrees can break the symmetry and lead to a distinct short-lifetime state! During floating, we further reveal that air leakage under droplet is significantly affected by liquid boundary, which has rarely been considered in similar problems. More interestingly, our substrate also exhibits non-adhesive properties: a droplet can bounce thousands of times under external vibration, and skids a long distance without coalescence. This study improves the fundamental understanding of droplet-substrate interaction, and suggests a new approach to realize non-adhesive surfaces for droplet.