| 초록 |
During the past three decades, a lot of experimental and computational works elucidating the behavior of the electrified drop have become available in literature [1-3]. As a result, we can fairly predict the behavior of conducting drop immersed in an insulating medium. In contrast, in the case of a less conducting drop suspended in a more conducting continuous phase, only a scare attention has been paid in an experimental point of view. This is partially due to the fact that the dielectric breakdown occurs easily when the medium is not highly insulating. In almost of previous studies, the effect of rotation of drop induced by electric field has not been considered. Recently, Krause and Chandratreya [4] showed that the rotational motion of the drop can alter the deformation behavior of the drop. According to the authors, the electrorotation can suppress the deformation perpendicular to the applied field direction. This is probably due to the fact that the rotation of the droplet interferes with the electrohydrodynamic flow along the interface between the droplet and the continuous phase. In this study, we consider the electric-field-induced rotation of the less conducting drop suspended in a more conducting drop and its consequences on the deformation and burst behavior of the drop under the action of dc electric field in an experimental point of view. Due to the lack of theoretical background on the electrorotation of deformable particles, we cannot fully analyze our experimental data on the basis of well-developed theoretical framework. Instead, in the following sections, we will introduce the well-known theory on the electrorotation of rigid sphere in a dc electric field and discuss the deviation from theory which is probably resulted from nonspherical, that is, oblate shape of the drop or dissipation of rotational energy due to the viscous flow inside the drop. We will also discuss the failure of Taylor’s leaky dielectric theory when the rotation motion of drop exists.
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