Effect of surface tension gradient driven convection in a laser melt pool: Three‐dimensional perturbation model

1988 ◽  
Vol 64 (11) ◽  
pp. 6166-6174 ◽  
Author(s):  
C. L. Chan ◽  
J. Mazumder ◽  
M. M. Chen
Keyword(s):  
Surface Tension ◽  
Three Dimensional ◽  
Surface Tension Gradient ◽  
Perturbation Model ◽  
Melt Pool ◽  
Effect Of Surface

scholarly journals Sensitivity of Thermal Predictions to Uncertain Surface Tension Data in Laser Additive Manufacturing

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
J. Coleman ◽  
A. Plotkowski ◽  
B. Stump ◽  
N. Raghavan ◽  
A. S. Sabau ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Fluid Flow ◽  
Additive Manufacturing ◽  
Current Model ◽  
Surface Tension Gradient ◽  
Process Conditions ◽  
Conductive Heat ◽  
Melt Pool ◽  
Super Alloy

Abstract To understand the process-microstructure relationships in additive manufacturing (AM), it is necessary to predict the solidification characteristics in the melt pool. This study investigates the influence of Marangoni driven fluid flow on the predicted melt pool geometry and solidification conditions using a continuum finite volume model. A calibrated laser absorptivity was determined by comparing the model predictions (neglecting fluid flow) against melt pool dimensions obtained from single laser melt experiments on a nickel super alloy 625 (IN625) plate. Using this calibrated efficiency, predicted melt pool geometries agree well with experiments across a range of process conditions. When fluid mechanics is considered, a surface tension gradient recommended for IN625 tends to overpredict the influence of convective heat transfer, but the use of an intermediate value reported from experimental measurements of a similar nickel super alloy produces excellent experimental agreement. Despite its significant effect on the melt pool geometry predictions, fluid flow was found to have a small effect on the predicted solidification conditions compared to processing conditions. This result suggests that under certain circumstances, a model only considering conductive heat transfer is sufficient for approximating process-microstructure relationships in laser AM. Extending the model to multiple laser passes further showed that fluid flow also has a small effect on the solidification conditions compared to the transient variations in the process. Limitations of the current model and areas of improvement, including uncertainties associated with the phenomenological model inputs are discussed.

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.

On forced three-dimensional surface waves in a channel in the presence of surface tension

1974 ◽  
Vol 75 (3) ◽  
pp. 405-426 ◽  
Author(s):  
P. F. Rhodes-Robinson
Keyword(s):  
Surface Tension ◽  
Velocity Potential ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Dimensional Solution ◽  
Surface Slopes ◽  
Infinite Region ◽  
Wave Maker ◽  
Effect Of Surface

AbstractIn this paper wave-maker theory including the effect of surface tension is determined for three-dimensional motion of water in a semi-infinite rectangular channel with outgoing surface wave modes allowed for at infinity; the motion is generated by a harmonically oscillating vertical plane wave-maker at the end of the channel and the cases of both infinite and finite constant depth are treated. The solution of the boundary-value problem for the velocity potential is more complicated in the presence of surface tension due mainly to the additional effect of the channel walls at which the normal free surface slopes are prescribed—as also is the slope at the wave-maker—to ensure uniqueness. The simpler three-dimensional solution for a semi-infinite region—obtained long ago by Sir Thomas Havelock in the absence of surface tension for the case of infinite depth—is also noted.

Numerical Simulation of Laminar Liquid Film Condensation in a Horizontal Circular Minichannel

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
E. Da Riva ◽  
D. Del Col
Keyword(s):  
Surface Tension ◽  
Liquid Film ◽  
Three Dimensional ◽  
Film Condensation ◽  
Interface Temperature ◽  
Condensation Process ◽  
Uniform Wall Temperature ◽  
Uniform Interface ◽  
Uniform Wall ◽  
Effect Of Surface

A three-dimensional volume of fluid (VOF) simulation of condensation of R134a inside a 1 mm i.d. minichannel is presented. The minichannel is horizontally oriented and the effect of gravity is taken into account. Simulations have been run both with and without taking into account surface tension. A uniform interface temperature and a uniform wall temperature have been fixed as boundary conditions. The mass flux is G = 100 kg m−2 s−1 and it has been assumed that the flow is laminar inside the liquid phase while turbulence inside the vapor phase has been handled by a modified low Reynolds form of the k–ω model. The fluid is condensed till reaching 0.45 vapor quality. The flow is expected to be annular without the presence of waves, therefore the problem was treated as steady state. Computational results displaying the evolution of vapor–liquid interface and heat transfer coefficient are reported and validated against experimental data. The condensation process is found to be gravity dominated, while the global effect of surface tension is found to be negligible. At inlet, the liquid film is thin and evenly distributed all around the tube circumference. Moving downstream the channel, the film thickness remains almost constant in the upper half of the minichannel, while the film at the bottom of the pipe becomes thicker because the liquid condensed at the top is drained by gravity to the bottom.

Effect of surface tension on melt pool dynamics during laser pulse interaction

2006 ◽  
Vol 39 (3) ◽  
pp. 590-595 ◽  
Author(s):  
V V Semak ◽  
G A Knorovsky ◽  
D O MacCallum ◽  
R Allen Roach
Keyword(s):  
Surface Tension ◽  
Laser Pulse ◽  
Melt Pool ◽  
Laser Pulse Interaction ◽  
Effect Of Surface ◽  
Pulse Interaction

DECOUPLING THE EFFECT OF SURFACE TENSION AND VISCOSITY ON SPRAY CHARACTERISTICS UNDER DIFFERENT AMBIENT PRESSURES: NEAR-NOZZLE BEHAVIOR AND MACROSCOPIC CHARACTERISTICS

2019 ◽  
Vol 29 (7) ◽  
pp. 629-654
Author(s):  
Zehao Feng ◽  
Shangqing Tong ◽  
Chenglong Tang ◽  
Cheng Zhan ◽  
Keiya Nishida ◽  
...  
Keyword(s):  
Surface Tension ◽  
Spray Characteristics ◽  
Effect Of Surface
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