The particle image velocimetry of vortical electrohydrodynamic flows of oil near a high-voltage electrode tip

Perri, Anthony E.; Sankaran, A. N.; Staszel, Christopher; Schick, Rudolf J.; Mashayek, Farzad; Yarin, Alexander L.

doi:10.1007/s00348-020-03125-z

Cited by 8 publications

(28 citation statements)

References 24 publications

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“…For example, the Moffatt-type vortices in thermocapillary convection were analysed by Davis (1989) and Kuhlmann, Nienhüser & Rath (1999). As mentioned above, the Moffatt-like eddies in EHD flows have been reported by Perri et al (2020Perri et al ( , 2021 in their experiments and simulations. In order to help the reader to understand the EHD flows in general, we will introduce below a literature survey of the EHD flows and then discuss in detail the work of Perri et al (2020Perri et al ( , 2021.…”

Section: Moffatt Eddiesmentioning

confidence: 64%

“…In the aforementioned works on the blade-plate or needle-plate EHD configuration, the Moffatt eddies have not been mentioned or characterised. It was Perri et al (2020Perri et al ( , 2021 who first discussed the Moffatt eddies in the needle-plate EHD flow. In their experiment, the flow was induced in a canola oil between a high-voltage needle electrode and a grounded plate.…”

Section: Ehd Flows In a Blade/needle-plate Configurationmentioning

confidence: 99%

“…They also observed transient flow phenomena, indicative of a flow bifurcation to another state. Finally, Perri et al (2020) also performed numerical simulations of the EHD flow corresponding to their experimental set-up. They presented numerical results on the electric field strength magnitude and charge density.…”

Section: Ehd Flows In a Blade/needle-plate Configurationmentioning

confidence: 99%

“…After this seminal work, Moffatt-like eddies have been observed and studied in many other flow settings, such as the flow in a sudden expansion (Alleborn et al 1997), backward-facing step flows (Biswas, Breuer & Durst 2004) and lid-driven cavity flows (Biswas & Kalita 2018). In the context of electrohydrodynamics (EHD) flows, the Moffatt-like eddies were observed only very recently by Perri et al (2020Perri et al ( , 2021 in their experiments. Their experimental device consists of a grounded plate and a needle electrode placed vertically above it.…”

Section: Introductionmentioning

confidence: 99%

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Moffatt eddies in electrohydrodynamics flows: numerical simulations and analyses

Sun

Zhang

2022

J. Fluid Mech.

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We study numerically a sequence of eddies in two-dimensional electrohydrodynamics (EHD) flows of a dielectric liquid, driven by an electric potential difference between a hyperbolic blade electrode and a flat plate electrode (or the blade–plate configuration). The electrically driven flow impinges on the plate to generate vortices, which resemble Moffatt eddies (Moffatt, J. Fluid Mech., vol. 18, 1964, pp. 1–18). Such a phenomenon in EHD was first reported in the experimental work of Perri et al. (J. Fluid Mech., vol. 900, 2020, A12). We conduct direct numerical simulations of the EHD flow with three Moffatt-type eddies in a large computational domain at moderate electric Rayleigh numbers ( $T$ , quantifying the strength of the electric field). The ratios of size and intensity of the adjacent eddies are examined, and they can be compared favourably to the theoretical prediction of Moffatt; interestingly, the quantitative comparison is remarkably accurate for the two eddies in the far field. Our investigation also shows that a larger $T$ strengthens the vortex intensity, and a stronger charge diffusion effect enlarges the vortex size. A sufficiently large $T$ can further result in an oscillating flow, consistent with the experimental observation. In addition, a global stability analysis of the steady blade–plate EHD flow is conducted. The global mode is characterised in detail at different values of $T$ . When $T$ is large, the confinement effect of the geometry in the centre region may lead to an increased oscillation frequency. This work contributes to the quantitative characterisation of the Moffatt-type eddies in EHD flows.

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Section: Moffatt Eddiesmentioning

confidence: 64%

Section: Ehd Flows In a Blade/needle-plate Configurationmentioning

confidence: 99%

Section: Ehd Flows In a Blade/needle-plate Configurationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Moffatt eddies in electrohydrodynamics flows: numerical simulations and analyses

Sun

Zhang

2022

J. Fluid Mech.

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“…聚苯乙烯微球 [20] 。Chrikov 等对另一种维恩-昂萨格效应泵流动以及针-板结构电荷注入-传导机制电对流进行了 PIV 流场测量，直径 1-10 微米的硼硅酸盐空心球作为示踪粒子 [82,83] 。法国普瓦捷大学 Louste 等人较为系统地开展了介电液体电流动 PIV 测量工作，讨论了示踪粒子材料和浓度对测量结果的影响 [84,85] 。他们早期研究由电荷注入引起的流动 [86] ，近年来开始关注电导机制引起的流动 [87] 以及电荷注入-传导的过渡过程 [43] 。图 14 展示了一个封闭墙体内，9 对非对称平嵌电极(一对电极宽度分别为 1.3mm 和 3.8mm) [88,89] 。电导泵 PIV 测量工作还较少，且都是在封闭腔体内进行，没有外部流动。另外，PIV 测量结果显示简单的平板嵌入电极电导泵在低电压下的流场结构也很混乱 [86,87] ，说明电导泵内复杂流动特征和机理还有待深入研究。其他更复杂电极结构电导泵 PIV 测量还未有开展。 measured by PIV in a confined cavity [87] 微尺度电导泵(电极间距为几十微米到几百微…”

Section: 示了电极结构设计对电导泵性能有重要影响。unclassified