Breakup of a conducting drop in a uniform electric field

2014 ◽  
Vol 754 ◽  
pp. 550-589 ◽  
Author(s):  
Rahul B. Karyappa ◽  
Shivraj D. Deshmukh ◽  
Rochish M. Thaokar
Keyword(s):  
Steady State ◽  
Numerical Analysis ◽  
Electric Field ◽  
Viscosity Ratio ◽  
Uniform Electric Field ◽  
Shape Prior ◽  
Capillary Stress ◽  
Electric Stress ◽  
Dc Electric Field ◽  
Axisymmetric Shape

AbstractA conducting drop suspended in a viscous dielectric and subjected to a uniform DC electric field deforms to a steady-state shape when the electric stress and the viscous stress balance. Beyond a critical electric capillary number $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\mathit{Ca}$, which is the ratio of the electric to the capillary stress, a drop undergoes breakup. Although the steady-state deformation is independent of the viscosity ratio $\lambda $ of the drop and the medium phase, the breakup itself is dependent upon $\lambda $ and $\mathit{Ca}$. We perform a detailed experimental and numerical analysis of the axisymmetric shape prior to breakup (ASPB), which explains that there are three different kinds of ASPB modes: the formation of lobes, pointed ends and non-pointed ends. The axisymmetric shapes undergo transformation into the non-axisymmetric shape at breakup (NASB) before disintegrating. It is found that the lobes, pointed ends and non-pointed ends observed in ASPB give way to NASB modes of charged lobes disintegration, regular jets (which can undergo a whipping instability) and open jets, respectively. A detailed experimental and numerical analysis of the ASPB modes is conducted that explains the origin of the experimentally observed NASB modes. Several interesting features are reported for each of the three axisymmetric and non-axisymmetric modes when a drop undergoes breakup.

scholarly journals Liquid toroidal drop under uniform electric field

2017 ◽  
Vol 473 (2202) ◽  
pp. 20160633 ◽  
Author(s):  
Michael Zabarankin
Keyword(s):  
Surface Tension ◽  
Electric Field ◽  
Dielectric Constants ◽  
Uniform Electric Field ◽  
Normal Velocity ◽  
Spherical Drop ◽  
Electric Stress ◽  
Freely Suspended ◽  
Major Radius ◽  
External Forces

The problem of a stationary liquid toroidal drop freely suspended in another fluid and subjected to an electric field uniform at infinity is addressed analytically. Taylor’s discriminating function implies that, when the phases have equal viscosities and are assumed to be slightly conducting (leaky dielectrics), a spherical drop is stationary when Q =(2 R 2 +3 R +2)/(7 R 2 ), where R and Q are ratios of the phases’ electric conductivities and dielectric constants, respectively. This condition holds for any electric capillary number, Ca E , that defines the ratio of electric stress to surface tension. Pairam and Fernández-Nieves showed experimentally that, in the absence of external forces (Ca E =0), a toroidal drop shrinks towards its centre, and, consequently, the drop can be stationary only for some Ca E >0. This work finds Q and Ca E such that, under the presence of an electric field and with equal viscosities of the phases, a toroidal drop having major radius ρ and volume 4 π /3 is qualitatively stationary—the normal velocity of the drop’s interface is minute and the interface coincides visually with a streamline. The found Q and Ca E depend on R and ρ , and for large ρ , e.g. ρ ≥3, they have simple approximations: Q ∼( R 2 + R +1)/(3 R 2 ) and Ca E ∼ 3 3 π ρ / 2   ( 6  ln  ⁡ ρ + 2  ln ⁡ [ 96 π ] − 9 ) / ( 12  ln  ⁡ ρ + 4  ln ⁡ [ 96 π ] − 17 )   ( R + 1 ) 2 / ( R − 1 ) 2 .

Pyroelectric Properties of Alanine Doped TGS Single Crystalline Thick Films under Constant Electric Stress

2001 ◽  
Vol 688 ◽  
Author(s):  
Lucian Pintilie ◽  
Ion Matei ◽  
Ioana Pintilie ◽  
Horia V. Alexandru ◽  
Ciceron Berbecaru
Keyword(s):  
Electric Field ◽  
Curie Point ◽  
Thick Films ◽  
Bias Field ◽  
Pyroelectric Coefficient ◽  
Pyroelectric Properties ◽  
Electric Stress ◽  
Pyroelectric Current ◽  
Dc Electric Field ◽  
Internal Bias

AbstractPyroelectric properties of triglycine sulfate (TGS) thick films, separately doped with L and D alanine were investigated. Internal bias field of about 1 kV/cm, induced by the two dopants, stabilize the polarization in the opposite direction on the ferroelectric axis. Pyroelectric current (under constant stress) was recorded with a computer controlled Keithley 6517 electrometer, crossing up and down the Curie point. A reverse external electric field was applied on doped materials during heating, crossing up the Curie point. It is shown that the pyroelectric coefficient can be increased about four times at room temperature under un optimized DC electric field applied on the pyroelectric wafer.

Bubble Formation in a DC Electric Field

2008 ◽  
Author(s):  
Feng Chen ◽  
Yaozu Song ◽  
Yao Peng
Keyword(s):  
Aspect Ratio ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Bubble Growth ◽  
Growth Process ◽  
Major Axis ◽  
Minor Axis ◽  
Electric Stress ◽  
Dc Electric Field

The effect of a DC electric field on the formation and the characteristics of a nitrogen bubble injected from an orifice were studied experimentally and theoretically. This study was the first to divide the bubble growth process into four stages (waiting, expansion, deformation and detachment) according to the variation of the bubble shape in order to analyze the bubble behavior in the electric field. During the waiting stage, the waiting interval decreases significantly as the electric field strength rises. In the expansion stage, the minor axis reaches a maximum that decreases with increasing the electric field strength. Within the deformation stage, the major axis achieves its maximum and so does the aspect ratio. As the electric field strength rises, both the maximums of the major axis and the aspect ratio increase. At the detachment stage, as the electric field strength is intensified, the major axis lengthens, the minor axis shortens and the aspect ratio lengthens. From the waiting stage to the detachment stage, the effect of the electric field on the major axis of the bubble is marginal, while with increasing the electric field strength, the minor axis decreases distinctly and thus the aspect ratio increases. To employ the four-stage model, the bubble growth process was analyzed in detail under the electric field. The electric stress exerted on the bubble surface was calculated. The results show that the electric stress compresses the bubble equator and elongates the poles of the bubble, causing the bubble to elongate along the electric field direction.

A stabilizing effect of vanishing diffusion in electrohydrodynamics

1997 ◽  
Vol 8 (2) ◽  
pp. 217-227
Author(s):  
EDUARD FEIREISL
Keyword(s):  
Weak Solution ◽  
Steady State ◽  
Electric Field ◽  
Diffusion Coefficients ◽  
Dielectric Liquid ◽  
Recombination Process ◽  
Homogeneous Steady State ◽  
Stabilizing Effect ◽  
Dc Electric Field ◽  
Spatially Homogeneous

We consider a model of the motion of a viscous dielectric liquid subjected to a DC electric field when the bulk conduction results from the presence of a dissociation-recombination process. It is shown that any weak solution approaches a neighbourhood of a spatially homogeneous steady state with radius r≈(d+ +d−)&14frac;, where d+, d− are the diffusion coefficients.

Numerical Analysis of the Effect of Non Uniform Electric Field on the Trajectory of Micro Water Jet

2015 ◽  
Author(s):  
Satyabrata Mohanty ◽  
Kornel F. Ehmann ◽  
Jian Cao
Keyword(s):  
Numerical Analysis ◽  
Electric Field ◽  
Jet Impingement ◽  
Water Jet ◽  
Uniform Electric Field ◽  
Static Electric Field ◽  
Liquid Dielectrophoresis ◽  
Fine Control ◽  
Unique Approach ◽  
And Control

In spite of its inherent advantages as a manufacturing tool, water-jet has not been extensively applied to the field of micro-manufacturing due to its low tolerance and poor control of the position of jet impingement. This paper explores the possibility of using the phenomenon of liquid dielectrophoresis to deflect and control the trajectory of a water jet in air. An approach is suggested using a localized non-uniform static electric field over a micro water jet with diameters in the range of 25–100 micrometers. The water jet has been modelled as a thin dielectric column and the numerical analysis of the electric field distribution has been carried out using COMSOL to analyze the generated forces and predict the scale of deflection of the jet. This unique approach of harnessing the polar nature of water using the phenomenon of dielectrophoresis might be useful in achieving fine control of the water jet’s trajectory especially in micro water jet material processing.

scholarly journals On the Drift Velocity of Electrons in a Gas

1972 ◽  
Vol 25 (3) ◽  
pp. 329
Author(s):  
SL Paveri-Fontana
Keyword(s):  
Steady State ◽  
Electric Field ◽  
Drift Velocity ◽  
Isotropic Scattering ◽  
Uniform Electric Field ◽  
Present Communication ◽  
Steady State Distribution ◽  
State Distribution ◽  
Neutral Gas

In a recent paper, Crompton, Elford, and Robertson (1970; hereafter referred to as CER) considered certain questions concerning the steady-state distribution of electrons moving in a neutral gas under the influence of a uniform electric field E. The present communication comments on some aspects of the error discussion in the Appendix of the paper by CER. The analysis will be restricted to the case of isotropic scattering.

Effect of Viscosity Ratio on the Electric-Field-Driven Enhancement of Heat/Mass Transfer to a Spherical Drop

2012 ◽  
Author(s):  
Mohamed R. Abdelaal ◽  
Milind A. Jog
Keyword(s):  
Mass Transfer ◽  
Electric Field ◽  
Mass Transport ◽  
Heat Mass Transfer ◽  
Viscosity Ratio ◽  
Continuous Phase ◽  
Uniform Electric Field ◽  
Dielectric Fluid ◽  
Periodic Electric Field ◽  
Time Periodic

The effect of viscosity ratio on the electric-field-driven enhancement of heat/mass transfer to a spherical liquid drop of one dielectric fluid from another immiscible dielectric fluid is computationally investigated in this paper. The flow field is considered to be in the Stokes regime and the energy (species) conservation equations in the continuous phase are solved numerically using a fully implicit finite volume method. Results for flow outside the drop, transient temperature distributions, Nusselt number variations, and heat/mass transfer enhancement are presented for Peclet numbers varying from 10 to 500, dimensionless electric field frequency from 50 to 1000, and the ratio of viscosity of the continuous to the dispersed phase varying from 0.1 to 50. Steady and non-uniform unsteady electric fields are considered. The computational simulations show that when viscosity of the drop is lower than the viscosity of the surrounding fluid, a steady uniform electric field is more effective in enhancement of heat/mass transport compared to a non-uniform time periodic electric field. Conversely, when the continuous phase is less viscous than the drop, the non-uniform time periodic electric field provides improved heat/mass transport than the steady uniform electric field.

Sign in / Sign up

Export Citation Format

Share Document