以荷叶作为二级微纳米结构表面，对纳米流体在荷叶表面上的动态行为特性进行了研究。通过控制垂直振动台施加能量，驱动液滴在微纳米结构表面运动。由高速摄影捕捉图片，发现在液滴受迫振动过程中，在一定的振动频率（30~90 Hz）和振动幅值（0.2~2.0 mm）下，液滴会从微纳米结构表面跃起而脱离，即液滴在微纳米结构表面运动过程中，液滴的浸润状态发生了向Cassie（液滴悬浮在表面微结构上）状态的转变。此外，由于施加的外界振动频率不同，液滴的振动模式阶数j出现j=3/2向j=2的转变。结合实验以及液滴固有频率模型，发现振动液滴在共振频率（40 Hz）时发生脱离所需能量最小（0.39 mm）。通过对液滴三相接触线进行力学分析，得到了液滴在共振时发生浸润状态转变的力学特征。

With the surface of lotus leaves serving as the surface of secondary micro/nano structures,the dynamic behavior of a nanofluid on the surface of lotus leaves was investigated.Through controlling the amount of energy applied by a vertical vibration stand,the movement of the liquid droplets on the surface of the micro/nano structures was controlled.By using a high speed camera,photos were captured and it has been found that in the process of forced vibration of liquid droplets,at a certain vibration frequency (30-90 Hz) and vibration amplitude (0.2-2.0 mm),the liquid droplets will be leaped up and separated from the surface of the micro/nano structures,i.e.in the process of the movement of the liquid droplets on the surface of the micro/nano structures,the soaking state of the liquid droplets will undergo a transition to the Cassie state.In addition,due to various vibration frequencies applied from the outside world,the movement mode j of the liquid droplets will be changed from j=3/2 to j=2.In combination with the tests and an intrinsic frequency model for liquid droplets,it has been found that the amount of energy required for separation of the liquid droplets in vibration at the resonant frequency （40 Hz） will be the minimum (0.39mm).Through conducting a dynamic analysis of the threephase contact line of the liquid droplets,the mechanical characteristics of the liquid droplets in resonance during a transition of the soaking state were obtained.

TK474.8

国家自然科学基金（51176123）