On methods to reduce spurious currents within VOF solver frameworks. Part 1: a review of the static bubble/droplet

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Venkatesh Inguva ◽  
Andreas Schulz ◽  
Eugeny Y. Kenig
Keyword(s):  
Surface Tension ◽  
Aqueous Phase ◽  
Level Set ◽  
Capillary Number ◽  
Classical Case ◽  
Surface Tension Force ◽  
Artificial Viscosity ◽  
Special Treatment ◽  
Two Phase ◽  
Spurious Currents

AbstractIn two-phase flows in which the Capillary number is low, errors in the computation of the surface tension force at the interface cause Front-Capturing methods such as Volume of Fluid (VOF) and Level-Set (LS) to develop interfacial spurious currents. To better solve low Capillary number flows, special treatment is required to reduce such spurious currents. Smoothing the phase indicator field to more accurately compute the curvature or adding interfacial artificial viscosity are techniques that can treat this problem. This study explores OpenFOAM, Fluent and StarCCM+ VOF solvers for the classical case of a static bubble/droplet immersed in a continuous aqueous phase, with the focus on the ability of these solvers to adequately reduce spurious currents. The results are expected to be helpful for practicing chemical engineers who use multiphase CFD solvers in their work.

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.

Study on C–S and P–R EOS in pseudo-potential lattice Boltzmann model for two-phase flows

2017 ◽  
Vol 28 (09) ◽  
pp. 1750120 ◽  
Author(s):  
Yong Peng ◽  
Yun Fei Mao ◽  
Bo Wang ◽  
Bo Xie
Keyword(s):  
Surface Tension ◽  
Lattice Boltzmann ◽  
Equations Of State ◽  
Density Ratio ◽  
Maximum Density ◽  
Lattice Boltzmann Model ◽  
Two Phase Flows ◽  
Two Phase ◽  
Spurious Currents ◽  
Pseudo Potential

Equations of State (EOS) is crucial in simulating multiphase flows by the pseudo-potential lattice Boltzmann method (LBM). In the present study, the Peng and Robinson (P–R) and Carnahan and Starling (C–S) EOS in the pseudo-potential LBM with Exact Difference Method (EDM) scheme for two-phase flows have been compared. Both of P–R and C–S EOS have been used to study the two-phase separation, surface tension, the maximum two-phase density ratio and spurious currents. The study shows that both of P–R and C–S EOS agree with the analytical solutions although P–R EOS may perform better. The prediction of liquid phase by P–R EOS is more accurate than that of air phase and the contrary is true for C–S EOS. Predictions by both of EOS conform with the Laplace’s law. Besides, adjustment of surface tension is achieved by adjusting [Formula: see text]. The P–R EOS can achieve larger maximum density ratio than C–S EOS under the same [Formula: see text]. Besides, no matter the C–S EOS or the P–R EOS, if [Formula: see text] tends to 0.5, the computation is prone to numerical instability. The maximum spurious current for P–R is larger than that of C–S. The multiple-relaxation-time LBM still can improve obviously the numerical stability and can achieve larger maximum density ratio.

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.

A Sharp Surface Tension Modeling Method for Capillarity-Dominant Two-Phase Incompressible Flows

2007 ◽  
Author(s):  
Zhaoyuan Wang ◽  
Albert Y. Tong
Keyword(s):  
Surface Tension ◽  
Incompressible Flows ◽  
Jump Condition ◽  
Navier Stokes ◽  
Pressure Jump ◽  
Interfacial Flows ◽  
Two Phase ◽  
Navier Stokes Equation ◽  
Numerical Instabilities ◽  
Spurious Currents

A surface tension implementation algorithm for two-phase incompressible interfacial flows is presented in this study. The surface tension effect is treated as a jump condition at the interface and incorporated into the Navier-Stokes equation via a capillary pressure gradient. The interface is tracked by a coupled level set and volume-of-fluid (CLSVOF) method based on the finite-volume formulation on a fixed Eulerian grid. It has been shown in a stationary benchmark test the spurious currents are greatly reduced and the sharp pressure jump across the interface is well preserved. Numerical instabilities caused by the sharp treatment on a fixed grid are avoided. Several dynamic tests are performed to further validate the accuracy and versatility of the present method, the results of which are in good agreement with data reported in the literature.

The Hybrid Particle-Level-Set Method Applied to Two-Phase Flows

2006 ◽  
Author(s):  
Daniel Gaudlitz ◽  
Nikolaus A. Adams
Keyword(s):  
Surface Tension ◽  
Level Set Method ◽  
Level Set ◽  
Mass Conservation ◽  
Two Phase Flows ◽  
Two Phase ◽  
Hybrid Particle ◽  
Particle Level ◽  
Tension Term ◽  
Particle Level Set Method

The hybrid particle-level-set method was proposed by Enright et al. (2002) for improving the efficiency and accuracy of the original level-set method. In this paper, we examine the discretization of the surface-tension term and of the reinitialization procedure with respect to their effect on the mass-conservation properties of the overall method. We apply the hybrid particle-level-set method for the computation of two-phase flows and assess its performance with different parameter choices in comparison with the original level-set method.

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