论文标题
介电液滴碰撞的电水动力学与变异性润湿性表面
Electrohydrodynamics of dielectric droplet collision with variant wettability surfaces
论文作者
论文摘要
在本文中,我们报告了实验和半分析发现,以阐明介电液滴对超疏水SH和亲水性表面的电氢动力学EHD。涵盖了我们和电毛细管数的广泛数字CAE,以探索液滴影响EHD的各种状态。我们表明,对于固定的60,SH表面上的液滴反弹会随着电场强度的增加而抑制。在高CAE处,而不是通常的均匀径向收缩,而是在正交方向上更快地缩回电场,并沿电场的方向扩散。这样可以防止足够的动能积累以达到液滴反弹现象。对于我们和Ohnesorge数字的某些值哦,液滴在反弹期间表现出像运动一样的翻筋斗。随后,我们提出了一个半分析模型,以解释该场在SH表面上引起的反弹现象。在关键的CAE 4.0上方,EHD不稳定性通过轮辋的尖刺演变而引起指法模式。此外,讨论了在亲水性和SH表面上的扩散EHD。在两个润湿表面和固定的表面上,扩散因子显示出随着CAE的增加而增加的趋势。我们已经基于节能的分析模型制定了分析模型,以预测最大扩散直径。该模型预测与实验观察值保持了相当良好的一致性。最后,开发了一个相位图来解释在我们和CAE范围内的SH表面上的后撞液滴动力学。
In this article, we report experimental and semi analytical findings to elucidate the electrohydrodynamics EHD of a dielectric liquid droplet impact on superhydrophobic SH and hydrophilic surfaces. A wide range of Weber numbers We and electro-capillary numbers Cae is covered to explore the various regimes of droplet impact EHD. We show that for a fixed We 60, droplet rebound on SH surface is suppressed with increase of electric field intensity. At high Cae, instead of the usual uniform radial contraction, the droplets retract faster in orthogonal direction to the electric field and spread along the direction of the electric field. This prevents the accumulation of sufficient kinetic energy to achieve the droplet rebound phenomena. For certain values of We and Ohnesorge number Oh, droplets exhibit somersault like motion during rebound. Subsequently we propose a semi analytical model to explain the field induced rebound phenomenon on SH surfaces. Above a critical Cae 4.0, EHD instability causes fingering pattern via evolution of spire at the rim. Further, the spreading EHD on both hydrophilic and SH surfaces are discussed. On both wettability surfaces and for a fixed We, the spreading factor shows an increasing trend with increase in Cae. We have formulated an analytical model based on energy conservation to predict the maximum spreading diameter. The model predictions hold reasonably good agreement with the experimental observations. Finally, a phase map was developed to explain the post impact droplet dynamics on SH surfaces for a wide range of We and Cae.