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Electric-Discharge-Mediated Jetting, Crowning, Bursting, and Atomization of a Droplet
Physical Review Applied ( IF 4.6 ) Pub Date : 2021-01-06 , DOI: 10.1103/physrevapplied.15.014005
Bhaskarjyoti Sarma , Sunny Kumar , Amaresh Dalal , Dipankar N. Basu , Dipankar Bandyopadhyay

We observe bursting, crown or jet formation, and atomization phenomena when electric discharge is confined at the base of a liquid droplet. Emulating an electrowetting-on-dielectric setup, a hemispherical droplet is placed on a cathode-isolator platform while a pointed anode from the top stimulates the discharge inside the drop. Beyond a critical intensity of the applied electric field, the dielectric layer under the droplet suffers breakdown to generate the discharge. Within a few milliseconds, the electric discharge stimulates crown or jet formation or bursting of the droplet. A lower (higher) salt loading in the droplet at lower (higher) field intensity leads to the jetting (bursting). The crown formation happens only for an intermediate window of salt loadings and electric field intensities. The energy conversion efficiency is found to be approximately 25%30% for droplet bursting while the same is less than 2% for jet or crown formation. The experiments and simulations uncover that the location of the pointed electrode in the droplet and the separation distance of electrodes can be some crucial factors in varying the location of discharge, which eventually leads to the aforementioned flow morphologies. Further, the interplay between surface tension, viscous, and electric field forces inside the droplet is found to play crucial roles to engender the flow patterns. The setup transiently shows up the formation of end pinching of jets, microjets, high-aspect-ratio liquid threads, upward moving jet, liquid spikes riding on a crown rim, and capillary breakup of jets. Such electric-discharge-mediated droplet disintegration resembles closely the previously reported laser or plasma-induced phenomena. Further, with proper tuning of the aforementioned control parameters, the proposed methodology is expected to find its application in several cutting-edge technologies, such as inkjet printing, tissue ablation, or electroporation etc.

中文翻译:

放电介导的液滴喷射,隆起,破裂和雾化

当放电限制在液滴的底部时,我们会观察到破裂,冠状或射流形成以及雾化现象。模拟电介质上的电润湿设置,将半球形液滴放在阴极隔离器平台上,同时从顶部指向尖头的阳极会刺激液滴内部的放电。除了所施加的电场的临界强度之外,液滴下方的介电层遭受击穿以产生放电。在几毫秒内,放电会刺激冠或喷流的形成或液滴的破裂。在较低(较高)场强度下,液滴中较低(较高)的盐负荷会导致喷射(爆裂)。冠形成仅在盐负荷和电场强度的中间窗口发生。2530对于液滴破裂而言,而对于喷射或冠形成而言,其小于2%。实验和模拟发现,液滴中的尖端电极的位置和电极的分离距离可能是改变放电位置的一些关键因素,最终导致上述流动形态。此外,发现液滴内部的表面张力,粘性和电场力之间的相互作用对产生流动模式起着至关重要的作用。该设置会暂时显示出喷嘴,微喷嘴,高纵横比液体线,向上移动的喷嘴,顶冠边缘的液体尖峰和喷嘴的毛细管破裂的末端收缩的形成。这种放电介导的液滴崩解非常类似于先前报道的激光或等离子体诱导的现象。进一步,
更新日期:2021-01-06
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