Numerical and theoretical analyses of the dynamics of droplets driven by electrowetting on dielectric in a Hele-Shaw cell
Numerical and theoretical analyses of the dynamics of droplets driven by electrowetting on dielectric in a Hele-Shaw cell
复制标题
DOI：
10.1017/jfm.2018.16
复制
发表时间：
2018-02
影响因子：
3.7
通讯作者：
Yasufumi Yamamoto;T. Ito;T. Wakimoto;K. Katoh
中科院分区：
文献类型：
--
作者：
Yasufumi Yamamoto;T. Ito;T. Wakimoto;K. Katoh
对 Hele-Shaw 池中电介质电润湿 (EWOD) 的液滴运动进行了理论和数值分析。我们提出了一个简单的运动理论模型，它很好地描述了实验测量的低于饱和电压的液滴速度的电压依赖性。数值分析的模拟方法是通过使用 Young-Lippmann 方程来表示 EWOD 和广义纳维边界条件来表示前向跟踪方法中的移动接触线来构建的。通过调整滑移参数，目前的全三维数值模拟很好地再现了实验观察到的液滴的形状演变和运动速度。我们在各种形状和电压的数值实验中验证了所提出的理论模型。此外，我们从理论上分析了在模拟和实验中观察到的液滴运动开始时接触线的行为，并且我们能够很好地估计接触角变化的时间尺度。
Droplet movement by electrowetting on dielectric (EWOD) in a Hele-Shaw cell is analysed theoretically and numerically. We propose a simple theoretical model for the motion, which describes well the voltage dependency of droplet speed below the saturation voltage as measured experimentally. The simulation method for numerical analyses is constructed by using the Young–Lippmann equation to represent EWOD and the generalised Navier boundary condition to represent the moving contact line in the context of the front-tracking method. With an adjusted slip parameter, the present full three-dimensional numerical simulation reproduces well the shape evolution and movement speed of droplets as observed experimentally. We verify the proposed theoretical model in numerical experiments with various shapes and voltages. Furthermore, we analyse theoretically the behaviour of the contact line at the onset of droplet motion as observed in the simulation and experiment, and we are able to estimate very well the time scale on which the contact angle changes.