Breakup of electrified jets

2007 ◽  
Vol 588 ◽  
pp. 75-129 ◽  
Author(s):  
ROBERT T. COLLINS ◽  
MICHAEL T. HARRIS ◽  
OSMAN A. BASARAN
Keyword(s):  
Surface Tension ◽  
Three Dimensional ◽  
Surface Tension Force ◽  
Radial Electric Field ◽  
Temporal Analysis ◽  
Tension Force ◽  
Satellite Drops ◽  
Wide Range ◽  
Electrified Jets ◽  
Effect Of Surface

Breakup of electrified jets is important in applications as diverse as electrospraying, electroseparations and electrospray mass spectrometry. Breakup of a perfectly conducting, incompressible Newtonian liquid jet surrounded by a passive insulating gas that is stressed by a radial electric field is studied by a temporal analysis. An initially quiescent jet is subjected to axially periodic shape perturbations and the ensuing dynamics are followed numerically until pinch-off by both a three-dimensional but axisymmetric (two-dimensional) and a one-dimensional slender-jet algorithm. Results computed with these algorithms are verified against predictions from linear theory for short times. Breakup times, ratios of the sizes of the primary to satellite drops formed at pinch-off, and the Coulombic stability of these drops are reported over a wide range of electrical Bond numbers, NE (ratio of electric to surface tension force), Ohnesorge numbers, NOh (ratio of viscous to surface tension force), and disturbance wavenumbers, k. Effect of surface charge on interface overturning is investigated. Furthermore, the influence of electrostatic stresses on the dynamics of pinch-off and the mechanisms of satellite drop formation is also addressed.

A Viscoelastic VOF-PROST Code for the Study of Drop Deformation

Volume 3 ◽  
2004 ◽  
Author(s):  
Y. Renardy ◽  
M. Renardy ◽  
T. Chinyoka ◽  
D. B. Khismatullin ◽  
J. Li
Keyword(s):  
Surface Tension ◽  
Constitutive Equation ◽  
Viscoelastic Medium ◽  
Three Dimensional ◽  
Surface Tension Force ◽  
Volume Of Fluid ◽  
Tension Force ◽  
Drop Deformation ◽  
Volume Of Fluid Method ◽  
Viscoelastic Liquids

A volume of fluid method is developed with a parabolic representation of the interface for the surface tension force (VOF-PROST). This three-dimensional transient code is extended to treat viscoelastic liquids with the Oldroyd-B constitutive equation. Simulations of deformation for a Newtonian drop in a viscoelastic medium under shear are reported.

Numerical Analysis of Liquid Breakup and Drop Generation in Low Velocity Jets

2015 ◽  
Author(s):  
Sucharitha Rajendran ◽  
Milind A. Jog ◽  
Raj M. Manglik
Keyword(s):  
Surface Tension ◽  
Surface Tension Force ◽  
The Other ◽  
Viscous Force ◽  
Liquid Jet ◽  
Biological Applications ◽  
Liquid Stream ◽  
Low Velocity ◽  
Satellite Drops ◽  
Wide Range

Biological sprays and aerodynamically assisted bio-jets are increasingly employed in treatment of living cells and organisms for applications in regenerative medicine, tissue repair, and advanced therapeutics. The liquid used in biological applications cover a wide range of viscosities and surface tensions. Determining conditions that achieve steady and uniform drop distribution for a range of properties of the liquid jet is critical in advancing biological applications. In this study, numerical simulations of jet breakup are carried out using a modified volume of fluid (VOF) approach to capture the interface. The interplay of viscosity and surface tension is studied by varying liquid properties. Simulations show that a high viscosity jet stretches and elongates before a liquid segment detaches. Based on the thickness of the liquid thread connecting the detaching drop to the main liquid stream, two fundamentally different modes of liquid pinch off have been predicted: thick-thin and thin-thick. In the thick-thin mode, the liquid jet has a growing drop at its edge. As this drop grows in size, the liquid stream stretches till the drop is pinched off the liquid stream. In the other mode in addition to the pinch off of drops from the jet, ligaments of liquid break off. The change in the breakup mode is primarily governed by the relative magnitude of the viscous force compared to surface tension with high viscous force leading to thin-thick liquid stretching and pinch off. Thick-thin stretching is seen to produce slow moving satellite drops that merge backwards with the oncoming drop, while thin-thick stretching is noticed to result in faster satellite drops that merge forwards. On the other hand when surface tension force dominates, non-merging satellite drops are formed that move with a speed close to the primary drops.

Prediction of the Condensation Coefficient on Horizontal Integral-Fin Tubes

1985 ◽  
Vol 107 (2) ◽  
pp. 369-376 ◽  
Author(s):  
R. L. Webb ◽  
T. M. Rudy ◽  
M. A. Kedzierski
Keyword(s):  
Surface Tension ◽  
Theoretical Model ◽  
Surface Tension Force ◽  
Tension Force ◽  
Condensation Coefficient ◽  
Film Drainage ◽  
Predicted Values ◽  
Experimental Values ◽  
Fin Tubes

A theoretical model is developed for prediction of the condensation coefficient on horizontal integral-fin tubes for both high and low surface tension fluids. The model includes the effects of surface tension on film drainage and on condensate retention between the fins. First, the fraction of the tube circumference that is flooded with condensate is calculated. Typically, the condensation coefficient in the flooded region is negligible compared to that of the unflooded region. Then the condensation coefficient on the unflooded portion is calculated, assuming that surface tension force drains the condensate from the fins. The model is used to predict the R-11 condensation coefficient on horizontal, integral-fin tubes having 748, 1024, and 1378 fpm. The predicted values are within ±20 percent of the experimental values.

Inward Flow of Micro-Particles in an Evaporating Di-Dispersed Colloid Droplet on Hydrophilic Surface

2009 ◽  
Author(s):  
Jung-Yeul Jung ◽  
Young Won Kim ◽  
Jung Yul Yoo
Keyword(s):  
Surface Tension ◽  
Contact Line ◽  
Surface Tension Force ◽  
Nano Particles ◽  
Tension Force ◽  
Hydrophilic Surface ◽  
Micro Particles

It is well known that the liquid and the nanoparticles in an evaporating colloid droplet on the hydrophilic surface move radially outward for the contact line to maintain its position. However, the motion of micro-/nano-particles in an evaporating di-dispersed colloid droplet has not been reported to date. In this study, an experiment on an evaporating di-dispersed colloid droplet on the hydrophilic surface is carried out. It is found that nano-particles move radially outward and remain at the contact line while micro-particles move inward toward the center of the droplet. Further the mechanism of the micro-particles moving toward the center of the droplet is found to be due to the surface tension force of the liquid.

Computation of a Propagating Interface in Multiphase Flows Using an Adaptive Coupled Level Set Method

2002 ◽  
Author(s):  
Ruquan Liang ◽  
Satoru Komori
Keyword(s):  
Surface Tension ◽  
Level Set Method ◽  
Level Set ◽  
Multiphase Flows ◽  
Surface Tension Force ◽  
Numerical Results ◽  
Passive Transport ◽  
Effect Of Surface ◽  
Good Agreement ◽  
Numerical Strategy

We present a numerical strategy for a propagating interface in multiphase flows using a level set method combined with a local mesh adaptative technique. We use the level set method to move the propagating interface in multiphase flows. We also use the local mesh adaptative technique to increase the grid resolution at regions near the propagating interface and additionally at the regions near points of high curvature with a minimum of additional expense. For illustration, we apply the adaptive coupled level set method to a collection of bubbles moving under passive transport. Good agreement has been obtained in the comparision of the numerical results for the collection of bubbles using an adaptative grid with those using a single grid. We also apply the adaptive coupled level set method to a droplet falling on a step where it is important to accurately model the effect of surface tension force and the motion of the free-surface, and the numerical results agree very closely with available data.

Nonlinear deformation and breakup of stretching liquid bridges

1996 ◽  
Vol 329 ◽  
pp. 207-245 ◽  
Author(s):  
X. Zhang ◽  
R. S. Padgett ◽  
O. A. Basaran
Keyword(s):  
Surface Tension ◽  
Liquid Bridge ◽  
Method Of Lines ◽  
Inertial Force ◽  
Surface Tension Force ◽  
Tension Force ◽  
Geometrical Parameters ◽  
Liquid Density ◽  
Liquid Bridges ◽  
Disk Radius

In this paper, the nonlinear dynamics of an axisymmetric liquid bridge held captive between two coaxial, circular, solid disks that are separated at a constant velocity are considered. As the disks are continuously pulled apart, the bridge deforms and ultimately breaks when its length attains a limiting value, producing two drops that are supported on the two disks. The evolution in time of the bridge shape and the rupture of the interface are investigated theoretically and experimentally to quantitatively probe the influence of physical and geometrical parameters on the dynamics. In the computations, a one-dimensional model that is based on the slender jet approximation is used to simulate the dynamic response of the bridge to the continuous uniaxial stretching. The governing system of nonlinear, time-dependent equations is solved numerically by a method of lines that uses the Galerkin/finite element method for discretization in space and an adaptive, implicit finite difference technique for discretization in time. In order to verify the model and computational results, extensive experiments are performed by using an ultra-high-speed video system to monitor the dynamics of liquid bridges with a time resolution of 1/12 th of a millisecond. The computational and experimental results show that as the importance of the inertial force – most easily changed in experiments by changing the stretching velocity – relative to the surface tension force increases but does not become too large and the importance of the viscous force – most easily changed by changing liquid viscosity – relative to the surface tension force increases, the limiting length that a liquid bridge is able to attain before breaking increases. By contrast, increasing the gravitational force – most readily controlled by varying disk radius or liquid density – relative to the surface tension force reduces the limiting bridge length at breakup. Moreover, the manner in which the bridge volume is partitioned between the pendant and sessile drops that result upon breakup is strongly influenced by the magnitudes of viscous, inertial, and gravitational forces relative to surface tension ones. Attention is also paid here to the dynamics of the liquid thread that connects the two portions of the bridge liquid that are pendant from the top moving rod and sessile on the lower stationary rod because the manner in which the thread evolves in time and breaks has important implications for the closely related problem of drop formation from a capillary. Reassuringly, the computations and the experimental measurements are shown to agree well with one another.

scholarly journals Implementation of surface tension force in fluid flow during reactive rotational molding

2015 ◽  
Vol 9 (2) ◽  
pp. 131-148 ◽  
Author(s):  
A. Hamidi ◽  
S. Khelladi ◽  
A. illoul ◽  
M. Shirinbayan ◽  
F. Bakir ◽  
...  
Keyword(s):  
Surface Tension ◽  
Fluid Flow ◽  
Surface Tension Force ◽  
Tension Force ◽  
Rotational Molding ◽  
Reactive Rotational Molding
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