电场作用下液滴的动力学特征

Dynamic Characteristics of Droplet in Presence of Electric Field

基于漏电介质模型和润滑理论,建立了电场作用下两极板间液滴运动特征的理论模型,采用PDECOL数值模拟了不同底部电势下液滴的动力学特征及多种参数的影响,讨论了主要特征量的变化率。结果表明:线性底部电势的突出影响表现在促进液滴整体偏移现象上,具有减缓液滴铺展、抑制液膜破断的作用;非线性电势的影响体现在液滴自由界面呈波状形态,或液滴中心内陷,逐渐破裂为子液滴、并向两侧分离的特征,提高电毛细力数有助于分裂液滴、增大电极间距则可减缓液滴运动;交流电场作用下,液滴作周期性振荡运动、呈扁长外形,提高电压幅值加剧液滴破裂或重组特征。

Theoretical model was established based on the leaky dielectric model and lubrication theory to analyze the dynamic characteristics of a droplet between two electrode plates in the presence of electric field. The PDECOL code was used to perform numerical simulation and investigate the dynamic characteristics of a droplet under different types of bottom electric potential and the effects of important parameters,and the change rate of main characteristic quantity was discussed. The results show that the obvious effect of linear bottom electric potential is to promote the droplet deviation,to slow down spreading rate and to inhibit film rupture. The nonlinear electric potential leads to the wavy feature on the free interface,or the invagination of droplet center and then the droplet splits into small droplets and moves toward two sides. Increasing electric capillary force can promote the split of droplet,while expanding the distance between electrodes can slow down the droplet movement. Under the AC electric field,the droplet oscillates periodically,and presents as long flat shape; the droplet rupture or recombination can be intensified by the increase of voltage.