电润湿效应下液滴动态接触行为分析

Analysis of dynamic contact behavior of droplet under electrowetting effect

摘要:

为研究电润湿条件下液滴动态接触行为的动态变化机制,采用动态接触角理论,建立电润湿下液滴的数值模型,并对液滴动态接触行为进行分析,系统地研究体积和壁面条件对液滴动态行为的影响。结果表明:当液滴体积从2 μL增加到6 μL时,液滴接触半径的最大振幅从0.16 mm增加到0.23 mm,当液滴初始角度从100°增加到115°时,振幅从0.13 mm增加到0.18 mm;同时,滑移长度从0.5 μm增加到2 μm时,振幅最大值从0.21 mm增大到0.29 mm。液滴体积越大、壁面的阻力越小和疏水性越强,液滴具有更高的动能以及更大的振荡幅度。此外,液滴初始动能越大,液滴的振荡更加剧烈。通过揭示液滴在电润湿过程中的动态接触行为机制,为通过电润湿效应改善微通道传热特性的研究提供理论依据。

Abstract:

In order to study the dynamic change mechanism of droplet dynamic contact behavior under electrowetting conditions, the dynamic contact angle theory is used to establish a numerical model of droplet under electrowetting and the droplet transient behaviour is analysed. In particular, the effects of volume and wall conditions on the dynamic behaviour of droplet are systematically investigated. The results show that the maximum amplitude of the droplet contact radius increases from 0.16 mm to 0.23 mm when the droplet volume increases from 2 μL to 6 μL, and the amplitude increases from 0.13 mm to 0.18 mm when the initial droplet angle increases from 100° to 115°. At the same time, with the slip length from 0.5 μm increased to 2 μm, the maximum amplitude increases from 0.21 mm to 0.29 mm. The larger the droplet volume, the smaller the wall resistance, the stronger the hydrophobicity, and the higher the kinetic energy and the greater the oscillation amplitude of the droplet. By revealing the dynamic contact behavior mechanism of droplets in the process of electrowetting, a theoretical basis is provided for the study of improving the heat transfer characteristics of microchannels through the electrowetting effect.