scholarly journals On sharp surface force model: Effect of sharpening coefficient

2020 ◽  
Vol 3 (3) ◽  
pp. 226-232 ◽  
Author(s):  
Kurian J. Vachaparambil ◽  
Kristian Etienne Einarsrud
Keyword(s):  
Surface Tension ◽  
Capillary Rise ◽  
Surface Tension Force ◽  
Surface Force ◽  
Volume Of Fluid ◽  
Tension Force ◽  
Force Model ◽  
Relative Ease

Abstract Amongst the multitude of approaches available in literature to reduce spurious velocities in Volume of Fluid approach, the Sharp Surface Force (SSF) model is increasingly being used due to its relative ease to implement. The SSF approach relies on a user-defined parameter, the sharpening coefficient, which determines the extent of the smeared nature of interface used to determine the surface tension force. In this paper, we use the SSF model implemented in OpenFOAM® to investigate the effect of this sharpening coefficient on spurious velocities and accuracy of dynamic, i.e., capillary rise, and static bubble simulations. Results show that increasing the sharpening coefficient generally reduces the spurious velocities in both static and dynamic cases. Although static millimeter sized bubbles were simulated with the whole range of sharpening coefficients, sub-millimeter sized bubbles show nonphysical behavior for values larger than 0.3. The accuracy of the capillary rise simulations has been observed to change non-linearly with the sharpening coefficient. This work illustrates the importance of using an optimized value of the sharpening coefficient with respect to spurious velocities and accuracy of the simulation.

A Numerical Method for Capillarity-Driven Free Surface Flows

2005 ◽  
Author(s):  
Albert Y. Tong ◽  
Zhaoyuan Wang
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Level Set ◽  
Surface Tension Force ◽  
Surface Force ◽  
Volume Of Fluid ◽  
Free Surface Flows ◽  
Tension Force ◽  
Navier Stokes Equation ◽  
Spurious Currents

The continuum surface force (CSF) method has been extensively employed in the volume-of-fluid (VOF), level set (LS) and front tracking methods to model surface tension force. It is a robust method requiring relatively easy implementation. However, it is known to generate spurious currents near the interface that may lead to disastrous interface instabilities and failures of grid convergence. A different surface tension implementation algorithm, referred to as the pressure boundary method (PBM), is introduced in this study. The surface tension force is incorporated into the Navier-Stokes equation via a capillary pressure gradient while the free surface is tracked by a coupled level set and volume-of-fluid (CLSVOF) method. It has been shown that the spurious currents are greatly reduced by the present method with the sharp pressure boundary condition preserved. The numerical results of several cases have been compared with data reported in the literature and are found to be in a close agreement.

scholarly journals Comparison of Surface Tension Models for the Volume of Fluid Method

Processes ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 542 ◽  
Author(s):  
Kurian J. Vachaparambil ◽  
Kristian Etienne Einarsrud
Keyword(s):  
Surface Tension ◽  
Multiphase Flow ◽  
Capillary Rise ◽  
Surface Tension Force ◽  
Surface Force ◽  
Parallel Plates ◽  
Time Step ◽  
Mesh Resolution ◽  
Active Research ◽  
Spurious Currents

With the increasing use of Computational Fluid Dynamics to investigate multiphase flow scenarios, modelling surface tension effects has been a topic of active research. A well known associated problem is the generation of spurious velocities (or currents), arising due to inaccuracies in calculations of the surface tension force. These spurious currents cause nonphysical flows which can adversely affect the predictive capability of these simulations. In this paper, we implement the Continuum Surface Force (CSF), Smoothed CSF and Sharp Surface Force (SSF) models in OpenFOAM. The models were validated for various multiphase flow scenarios for Capillary numbers of 10 − 3 –10. All the surface tension models provide reasonable agreement with benchmarking data for rising bubble simulations. Both CSF and SSF models successfully predicted the capillary rise between two parallel plates, but Smoothed CSF could not provide reliable results. The evolution of spurious current were studied for millimetre-sized stationary bubbles. The results shows that SSF and CSF models generate the least and most spurious currents, respectively. We also show that maximum time step, mesh resolution and the under-relaxation factor used in the simulations affect the magnitude of spurious currents.

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 Heat Transfer of a Flow Confined by Wire Screen in Lithium Bromide Absorption Process

2014 ◽  
Vol 348 ◽  
pp. 40-50 ◽  
Author(s):  
Herbert Obame Mve ◽  
Romuald Rullière ◽  
Rémi Goulet ◽  
Phillippe Haberschill
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Numerical Analysis ◽  
Lithium Bromide ◽  
Surface Tension Force ◽  
Surface Force ◽  
Geometrical Parameters ◽  
Force Model ◽  
Vof Model ◽  
Static Contact

The present study deals with the numerical analysis of heat transfer inside a lithium bromide solution flowing down between finely meshed plastic wire screens. These screens confine the flow through capillary action while allowing the water vapor transfer inside an innovative absorber technology. The complex menisci shape formed on the confinement grid level, where the surface tension forces are of first importance, are reconstructed by a volume of fluid (VOF) model. A continuum surface force model is used to account for the surface tension force. A static contact angle is used to define the wall adhesion. A new algorithm, consisting to set an unique constant temperature at the liquid/vapour interface and to determine the evolution of heat transfer characteristics over the simulation domain, has been implemented and validated by analytical solutions. A parametric study has been conducted to determine the effect of the inlet velocity and the geometrical parameters (wire diameter and the number of divisions).

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.

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