A method for overcoming the surface tension time step constraint in multiphase flows II

2011 ◽  
Vol 68 (11) ◽  
pp. 1343-1361 ◽  
Author(s):  
M. Sussman
Keyword(s):  
Surface Tension ◽  
Multiphase Flows ◽  
Time Step ◽  
Tension Time

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.

GLOBAL EXISTENCE FOR PHASE TRANSITION PROBLEMS VIA A VARIATIONAL SCHEME

2004 ◽  
Vol 01 (04) ◽  
pp. 747-768
Author(s):  
CHRISTIAN ROHDE ◽  
MAI DUC THANH
Keyword(s):  
Phase Transition ◽  
Surface Tension ◽  
Initial Data ◽  
Time Discretization ◽  
Approximate Solutions ◽  
Implicit Time ◽  
Time Step ◽  
Dynamical Phase Transition ◽  
Transition Dynamics ◽  
Variational Scheme

We construct approximate solutions of the initial value problem for dynamical phase transition problems via a variational scheme in one space dimension. First, we deal with a local model of phase transition dynamics which contains second and third order spatial derivatives modeling the effects of viscosity and surface tension. Assuming that the initial data are periodic, we prove the convergence of approximate solutions to a weak solution which satisfies the natural dissipation inequality. We note that this result still holds for non-periodic initial data. Second, we consider a model of phase transition dynamics with only Lipschitz continuous stress–strain function which contains a non-local convolution term to take account of surface tension. We also establish the existence of weak solutions. In both cases the proof relies on implicit time discretization and the analysis of a minimization problem at each time step.

scholarly journals Effects of surface tension time-evolution for CCN activation of a complex organic surfactant

2020 ◽  
Vol 22 (2) ◽  
pp. 271-284 ◽  
Author(s):  
Jack J. Lin ◽  
Thomas B. Kristensen ◽  
Silvia M. Calderón ◽  
Jussi Malila ◽  
Nønne L. Prisle
Keyword(s):  
Surface Tension ◽  
Time Evolution ◽  
Water Activity ◽  
Bulk Water ◽  
Organic Surfactant ◽  
Tension Time ◽  
Complex Organic

Time-evolving partitioning effects on surface tension and bulk water activity cancel out in Köhler predictions of CCN activation of mixed NAFA–NaCl particles.

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 conservative solver for surface-tension-driven multiphase flows on collocated unstructured grids

2020 ◽  
Vol 401 ◽  
pp. 109025 ◽  
Author(s):  
Bin Xie ◽  
Peng Jin ◽  
Hiroki Nakayama ◽  
ShiJun Liao ◽  
Feng Xiao
Keyword(s):  
Surface Tension ◽  
Multiphase Flows ◽  
Unstructured Grids

scholarly journals Particle-Based Dynamic Water Drops with High Surface Tension in Real Time

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1265
Author(s):  
Ki-Hoon Kim ◽  
Jung Lee ◽  
Chang-Hun Kim ◽  
Jong-Hyun Kim
Keyword(s):  
Surface Tension ◽  
Real Time ◽  
Liquid Metals ◽  
High Surface ◽  
Computational Cost ◽  
Great Influence ◽  
Fluid Simulation ◽  
Control Surface ◽  
Time Step ◽  
High Surface Tension

Surface tension has a great influence on the shape of the fluid interface, and is an important physical characteristic in expressing not only liquids but also liquid metals such as mercury and gallium. In the field of physics-based particle fluid simulations, it is a challenging problem to express the high surface tension generated by fluid-air or fluid-solid interaction in real time. The main reasons for this are (1) The magnitude of the force that can be stably expressed in real-time fluid simulation is limited, so when the magnitude of the surface tension increases at a large time-step, the simulation stability decreases, and (2) If we use a small time-step, a stronger force can be expressed. However, it becomes difficult to operate in real time because the computational cost increases. Techniques were proposed to solve this problem for a few specific scenes, but there has not yet been a general approach that can reliably express high surface tension in various scenarios. In this paper, we propose a real-time particle-based fluid simulation framework that can efficiently and stably express high surface tension. Unlike the previous methods, we newly model the surface tension so that the strong surface tension force generated in the droplet area with a large curvature is applied evenly in the normal and tangent directions regardless of the size of the droplet. We also propose new pressure constraints that converge quickly and accurately using this force. Our method can be effectively used in various physics-based simulation scenarios because it can easily express and control surface tension effects that appear in materials such as liquid metal as well as water.

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