Numerical Investigation of Countercurrent Two-Phase Flows Using Three-Dimensional Volume-of-Fluid Simulations

2011 ◽  
Author(s):  
Gae¨l Gue´don ◽  
Emanuela Colombo ◽  
Fabio Inzoli
Keyword(s):  
Two Phase Flow ◽  
Three Dimensional ◽  
Volume Of Fluid ◽  
Immiscible Fluids ◽  
Vof Method ◽  
Operating Conditions ◽  
Bubble Columns ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase

Several engineering plants and components, such as nuclear reactors, boilers, bubble columns, chemical reactors or oil/gas wells may be characterized by two-phase flows. Appropriate and safe operation of these systems may be supported by the accurate prediction of the multiphase flow pattern with consistent estimation of the void fraction and flooding phenomenon. A preliminary approach for modeling flow patterns in countercurrent two-phase flows in vertical systems, based on the volume-of-fluid (VOF) method, is here presented. The general objective of the study is to investigate the feasibility of large scale two-phase systems simulations using the VOF method. The specific objective is to provide a first set of qualitative information about the fluid dynamics structures in this flow at specific operating conditions. Three-dimensional simulations are performed using a finite volume commercial CFD code. Validation of the numerical approach is achieved with experimental data taken from literature for typical air-water flows in bubble columns. The interaction of the downward water recirculation with the bubbles of air is indeed representative of a bubbly countercurrent two-phase flow and therefore may be a valuable test case. The use of the VOF method is here privileged, since no further closure relations are needed for exchange coefficients between the continuous and dispersed phases, and for breakup and coalescence of bubbles/drops. The validated model is therefore most likely applicable in complex situations where the flow behavior is unknown. Finally a specific analysis of a countercurrent two-phase flow is presented with the objective of simulating the flow within an industrial pipe where two immiscible fluids, with different density are injected. A fluid “A” is injected at the bottom of the pipe and it is supposed to exit the pipe in the upper part. A fluid “B”, immiscible in “A”, is injected at the top of the pipe in countercurrent and it is supposed not to influence the path of fluid “A” from inlet to the exit. Fluid “B” may be used for reacting somehow with fluid “A”, but in this paper only the fluid dynamic condition is considered.

A Combined Eulerian and Lagrangian Method for Prediction of Evaporating Sprays

2002 ◽  
Vol 124 (3) ◽  
pp. 481-488 ◽  
Author(s):  
M. Burger ◽  
G. Klose ◽  
G. Rottenkolber ◽  
R. Schmehl ◽  
D. Giebert ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Lagrangian Method ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Lagrangian Methods ◽  
Eulerian Method ◽  
Lagrangian Modeling

Polydisperse sprays in complex three-dimensional flow systems are important in many technical applications. Numerical descriptions of sprays are used to achieve a fast and accurate prediction of complex two-phase flows. The Eulerian and Lagrangian methods are two essentially different approaches for the modeling of disperse two-phase flows. Both methods have been implemented into the same computational fluid dynamics package which is based on a three-dimensional body-fitted finite volume method. Considering sprays represented by a small number of droplet starting conditions, the Eulerian method is clearly superior in terms of computational efficiency. However, with respect to complex polydisperse sprays, the Lagrangian technique gives a higher accuracy. In addition, Lagrangian modeling of secondary effects such as spray-wall interaction enhances the physical description of the two-phase flow. Therefore, in the present approach the Eulerian and the Lagrangian methods have been combined in a hybrid method. The Eulerian method is used to determine a preliminary solution of the two-phase flow field. Subsequently, the Lagrangian method is employed to improve the accuracy of the first solution using detailed sets of initial conditions. Consequently, this combined approach improves the overall convergence behavior of the simulation. In the final section, the advantages of each method are discussed when predicting an evaporating spray in an intake manifold of an internal combustion engine.

Flow-Induced Vibration Model for Steam Generator Tubes in Two-Phase Flow

2008 ◽  
Author(s):  
Njuki W. Mureithi ◽  
Soroush Shahriary ◽  
Michel J. Pettigrew
Keyword(s):  
Force Field ◽  
Steam Generator ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Fluid Force ◽  
Vibration Stability ◽  
Steam Generator Tubes

While steam generators operate in two-phase flow, the complex nature of the flow makes the prediction of flow-induced fluidelastic instability of steam generator tubes a challenging problem yet to be solved. In the work reported here, the quasi-static fluid force-field, which is the important unknown for two-phase flows, is measured in a rotated-triangle tube bundle for a series of void fractions and flow velocities. The forces are shown to be strongly dependent on void fraction, flow rates and relative tube positions. The fluid force field is then employed along with quasi-steady vibration stability models, originally developed for single phase flows, to model the two-phase flow problem and predict the critical instability velocity. The results are compared with dynamic vibration stability tests and are shown to be in good agreement. The present work uncovers some of the complexities of the fluid force field in two-phase flows. The database provides new potential to designers to estimate expected fluid dynamic loads under operating conditions. The force field data may also be applied in dynamic computations for tube wear simulations, replacing the simple Connors’ model which is currently used.

scholarly journals Direct simulations of two-phase flow experiments of different geometry complexities using Volume-of-Fluid (VOF) method

2019 ◽  
Vol 195 ◽  
pp. 820-827 ◽  
Author(s):  
X. Yin ◽  
I. Zarikos ◽  
N.K. Karadimitriou ◽  
A. Raoof ◽  
S.M. Hassanizadeh
Keyword(s):  
Two Phase Flow ◽  
Volume Of Fluid ◽  
Vof Method ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Experiments

An Improved Volume of Fluid Method for Two-Phase Flow Computations on Collocated Grid System

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Dong-Liang Sun ◽  
Yong-Ping Yang ◽  
Jin-Liang Xu ◽  
Wen-Quan Tao
Keyword(s):  
Two Phase Flow ◽  
Stokes Equations ◽  
Volume Of Fluid ◽  
Vof Method ◽  
Navier Stokes ◽  
Phase Flow ◽  
Volume Of Fluid Method ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Collocated Grid

An improved volume of fluid method called the accurate density and viscosity volume of fluid (ADV-VOF) method is proposed to solve two-phase flow problems. The method has the following features: (1) All operations are performed on a collocated grid system. (2) The piecewise linear interface calculation is used to capture interfaces and perform accurate estimations of cell-edged density and viscosity. (3) The conservative Navier–Stokes equations are solved with the convective term discretized by a second and third order interpolation for convection scheme. (4) A fractional-step method is applied to solve the conservative Navier–Stokes equations, and the BiCGSTAB algorithm is used to solve the algebraic equations by discretizing the pressure-correction equation. The above features guarantee a simple, stable, efficient, and accurate simulation of two-phase flow problems. The effectiveness of the ADV-VOF method is verified by comparing it with the conventional volume of fluid method with rough treatment of cell-edged density and viscosity. It is found that the ADV-VOF method could successfully model the two-phase problems with large density ratio and viscosity ratio between two phases and is better than the conventional volume of fluid method in this respect.

Three-dimensional mathematical modeling of dispersed two-phase flow using class method of population balance in bubble columns

2008 ◽  
Vol 32 (12) ◽  
pp. 3224-3237 ◽  
Author(s):  
Rachid Bannari ◽  
Fouzi Kerdouss ◽  
Brahim Selma ◽  
Abdelfettah Bannari ◽  
Pierre Proulx
Keyword(s):  
Mathematical Modeling ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Population Balance ◽  
Bubble Columns ◽  
Phase Flow ◽  
Two Phase

Numerical Analysis of Flow at Water Jacket of an Internal Combustion Engine

2011 ◽  
Vol 282-283 ◽  
pp. 702-705 ◽  
Author(s):  
De Zhi Zhang ◽  
Ying Ai Jin ◽  
De Yuan Su ◽  
Qing Gao
Keyword(s):  
Two Phase Flow ◽  
Cooling System ◽  
Combustion Engine ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Phase Flow ◽  
Three Dimensional Model ◽  
Two Phase ◽  
Water Jacket ◽  
Model And Simulation

With the increasing degree of the enhancement of engine, engine cooling system design is considered particularly important. This paper used an established three-dimensional model of an engine water jacket to study, and used UDF function in the two-phase flow of the CFD, describe the mathematical model and simulation the engine at different operating conditions, and get the water jacket flow rate transfer thermal process. Finally, the results of the relationship between the engine water jacket of boiling heat transfer and flow velocity have been studied, and the importance of using two-phase flow model has been summarized.

scholarly journals Comparison of the Volume of Fluid and CLSVOF Methods for the Assessment of Flow Boiling in Silicon Microgaps

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Daniel Lorenzini ◽  
Yogendra Joshi
Keyword(s):  
Phase Change ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Experimental Studies ◽  
Volume Of Fluid ◽  
Bubble Nucleation ◽  
Operating Conditions ◽  
Substrate Thickness ◽  
Phase Flow ◽  
Two Phase

The three-dimensional (3D) stacking of integrated circuits (ICs), and emergent microelectronic technologies require low-profile cooling solutions for the removal of relatively high heat fluxes. The flow boiling of dielectric refrigerants represents a feasible alternative to such applications by providing compatibility with the electrical interconnections, relatively uniform temperature profiles, and higher heat transfer coefficients than those obtained with single phase-cooling. Despite important experimental evidence in this area has been recently reported in the literature, the modeling of such has remained in basic and limited forms due to the associated complexities with the physics of two-phase flow with phase-change. In an effort to expand the studied possibilities for the modeling of flow boiling, the present investigation compares two different phase-tracking methods for the analysis of such phenomena: the volume of fluid (VOF) and the coupled level set—volume of fluid (CLSVOF) techniques. These interface tracking and reconstruction techniques are coupled with a phase change model that accounts for the mass and energy transfer source terms to the governing equations. The geometric domain is constituted by a silicon microgap 175 μm high with a substrate thickness of 50 μm, and populated with circular pin fins of 150 μm diameter, where the heat conduction is simultaneously solved with temperature dependent properties. The flow boiling regimes and their spatial and temporal evolution are compared between both methods by maintaining the operating conditions. Results indicate that both methods provide a good capability to predict major two-phase flow regimes observed in experimental studies with these types of arrangements. However, the CLSVOF offers a sharper interface reconstruction than the standard VOF method by predicting bubble nucleation and departure mechanisms more closely to experimental observations.

A Comparison of VOF and Euler-Euler Approaches in CFD Modelling of Two-Phase Flows With a Sharp Interface

2020 ◽  
Author(s):  
Luc Bertolotti ◽  
Richard Jefferson-Loveday ◽  
Stephen Ambrose ◽  
Evgenia Korsukova
Keyword(s):  
Shear Flows ◽  
Two Phase Flow ◽  
Thickness Distribution ◽  
Volume Of Fluid ◽  
Sharp Interface ◽  
Experimental Measurements ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Two Phases

Abstract In aero-engines, it is important to predict the behavior of shear flows in the different parts such as bearing chambers or gearboxes. In bearing chambers, the thickness distribution of wavy films is well studied as two-phase flows are still very hard to predict depending on the case. Experimental studies remain very expensive to carry out and Computational Fluid Dynamics (CFD) still struggles with two-phase flow prediction especially when a sharp interface between the two phases must be modelled. CFD is used to predict the oil film thickness distribution and interface velocity at different engine operating conditions. Currently Reynold-Averaged Navier-Stokes (RANS) CFD uses a semi-empirical method of turbulence damping, which is inaccurate for wavy films and so impacts the modelling of bearing chambers and gearboxes. With the objective of improving RANS models from Large Eddy Simulation (LES) methods, the Volume of Fluid (VOF) and Euler-Euler methods for two-phase flow modelling are investigated in this study. The Volume of Fluid (VOF) approach assumes a single set of momentum equations for the two phases and volume fractions are 1 or 0 everywhere except in the interface region. An alternative to VOF, is the Euler-Euler method with interface sharpening for shear flows. This approach assumes one set of momentum equations per phase but a shared field of pressure. The VOF and Euler-Euler approaches are compared in this study using LES with the CFD code OpenFOAM v6. The case study is based on experimental work investigating stratified flow in a horizontal channel that will be further detailed in the paper. In this study, a simplified 3D periodic channel filled with two distinct phases: air and water is used. A flow regime is studied in which flows are fully developed and the water phase has a much smaller velocity than the air phase in order to obtain a shear flow. Numerical results are compared with experimental measurements from the literature. With OpenFOAM, the VOF solver used for the study is interFoam and the Euler-Euler solver used is reacting-MultiphaseEulerFoam. Velocity profiles, shear-stress profiles and kinetic energy profiles are compared with experimental measurements for the assessment of the two flow solvers. Maps of vorticity magnitude are also provided to support the comparisons between the Euler-Euler and the VOF approaches as well as an appropriate vortex identification method.

A three-dimensional volume of fluid & level set (VOSET) method for incompressible two-phase flow

2015 ◽  
Vol 118 ◽  
pp. 293-304 ◽  
Author(s):  
Kong Ling ◽  
Zhao-Hui Li ◽  
Dong-Liang Sun ◽  
Ya-Ling He ◽  
Wen-Quan Tao
Keyword(s):  
Level Set ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Volume Of Fluid ◽  
Phase Flow ◽  
Fluid Level ◽  
Two Phase
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