The Prediction of Two-Phase Turbulence and Phase Distribution Phenomena Using a Reynolds Stress Model

1990 ◽  
Vol 112 (1) ◽  
pp. 107-113 ◽  
Author(s):  
M. Lopez de Bertodano ◽  
S.-J. Lee ◽  
R. T. Lahey ◽  
D. A. Drew
Keyword(s):  
Liquid Phase ◽  
Reynolds Stress ◽  
Lift Force ◽  
Phase Distribution ◽  
Liquid Velocity ◽  
Fluid Model ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Two Phase ◽  
Two Fluid Model

The void fraction distribution for turbulent bubbly air/water upflows and downflows in a pipe was analyzed using a three-dimensional two-fluid model. A τ − ε (i.e., Reynolds stress) turbulence model was used for the continuous (liquid) phase. The τ − ε transport equations yield all components of the Reynolds stress tensor for the liquid phase momentum equations. The effect of these stresses is to create a lateral pressure gradient that acts on the bubbles and effects their distribution. The lateral lift force on the bubbles has also been modelled. This lift force arises due to the relative motion of the bubble with respect to a nonuniform liquid velocity field. It has been observed experimentally that for upflows the bubbles concentrate near the wall while for downflows they move toward the center of the conduit. The model presented herein predicts these trends.

Phase Distribution in the Cap Bubble Regime in a Duct

2006 ◽  
Vol 128 (4) ◽  
pp. 811-818 ◽  
Author(s):  
Martin Lopez de Bertodano ◽  
Xiaodong Sun ◽  
Mamoru Ishii ◽  
Asim Ulke
Keyword(s):  
Turbulent Diffusion ◽  
Phase Distribution ◽  
Fluid Model ◽  
Three Dimensional ◽  
Interfacial Structure ◽  
Two Phase ◽  
Diffusion Force ◽  
Two Fluid Model ◽  
Bubble Regime ◽  
Two Fluid

The lateral phase distribution in the cap-bubbly regime was analyzed with a three-dimensional three-field two-fluid computational fluid dynamics (CFD) model based on the turbulence model for bubbly flows developed by Lopez de Bertodano et al. [1994, “Phase Distribution in Bubbly Two-Phase Flow in Vertical Ducts,” Int. J. Multiphase Flow, 20(5), pp. 805–818]. The turbulent diffusion of the bubbles is the dominant phase distribution mechanism. A new analytic result is presented to support the development of the model for the bubble induced turbulent diffusion force. New experimental data obtained by Sun et al. [2005, “Interfacial Structure in an Air-Water Planar Bubble Jet,” Exp. Fluids, 38(4), pp. 426–439] with the state-of-the-art four-sensor miniature conductivity probe in a vertical duct is used to validate the three-field two-fluid model CFD simulations.

Numerical Simulation of Boiling Two-Phase Flow in Tight-Lattice Rod Bundle by 3-Dimensional Two-Fluid Model Code ACE-3D

2008 ◽  
Author(s):  
Hiroyuki Yoshida ◽  
Takeharu Misawa ◽  
Kazuyuki Takase
Keyword(s):  
Void Fraction ◽  
Lift Force ◽  
Fluid Model ◽  
Phase Flow ◽  
Two Phase ◽  
Rod Bundle ◽  
Fraction Distribution ◽  
Two Fluid Model ◽  
Tight Lattice ◽  
Two Fluid

Two-fluid model can simulate two phase flow less computational cost than inter-face tracking method and particle interaction method. Therefore, two-fluid model is useful for thermal hydraulic analysis in large-scale domain such as a rod bundle. Japan Atomic Energy Agency (JAEA) develops three dimensional two-fluid model analysis code ACE-3D, which adopts boundary fitted coordinate system in order to simulate complex shape channel flow. In this paper, boiling two-phase flow analysis in a tight lattice rod bundle is performed by ACE-3D code. The parallel computation using 126CPUs is applied to this analysis. In the results, the void fraction, which distributes in outermost region of rod bundle, is lower than that in center region of rod bundle. At height z = 0.5 m, void fraction in the gap region is higher in comparison with that in center region of the subchannel. However, at height of z = 1.1m, higher void fraction distribution exists in center region of the subchannel in comparison with the gap region. The tendency of void fraction to concentrate in the gap region at vicinity of boiling starting point, and to move into subchannel as water goes through rod bundle, is qualitatively agreement with the measurement results by neutron radiography. To evaluate effects of two-phase flow model used in ACE-3D code, numerical simulation of boiling two-phase in tight lattice rod bundle with no lift force model (neglecting lift force acting on bubbles) is also performed. From the comparison of numerical results, it is concluded that the effects of lift force model are not so large on overall void fraction distribution in tight lattice rod bundle. However, higher void fraction distribution in center region of the subchannel was not observed in this simulation. It is concluded that the lift force model is important for local void fraction distribution in rod bundles.

Performance Analysis of Electric Submersible Pumps (ESP) Handling Two-Phase Mixtures

2002 ◽  
Author(s):  
Jose´ Caridad ◽  
Frank Kenyery
Keyword(s):  
Liquid Velocity ◽  
Fluid Model ◽  
Bubble Diameter ◽  
Petroleum Industry ◽  
Primary Concern ◽  
Cfd Simulations ◽  
Two Phase ◽  
Impeller Blade ◽  
Two Fluid Model ◽  
Complex Phenomena

Behavior of Electric Submersible Pumps (ESP) handling two-phase flow is a subject of primary concern, especially in the petroleum industry, where significant amounts of free gas may be found in oil wells production. Several attempts have been made in order to predict the performance of such kind of pumps, nevertheless, limited success has been achieved due to the complexity of the flow dynamics inside the impeller. Geometry, gas void fraction (GVF) and suction pressure seem to be the main parameters affecting ESP performance. Furthermore, the higher the GVF of the mixture is, the higher the degradation of head that it is experimented by the pump. This complex phenomena is not well understood so far. In this work, a two fluid model is used in 3D CFD simulations carried out in order to obtain the pressure, liquid velocity and gas velocity fields as well as the GVF distribution in an ESP impeller of known geometry; using flow rates, bubble diameter and GVF at the suction as independent variables and an incompressible fluid hypothesis. The gas pocket in the impeller blade reported from other researchers is obtained and comparison with experimental results has shown good agreement. The obtained variables from the simulations are the cornerstone that allows the prediction of the performance curve of the pump for different GVF and in this way, estimate the head degradation of the pump.

Simplification of Ensemble Averaged Two-Phase Flow with Heat and Mass Transfer Equations for Boiling in a Channel

2008 ◽  
Vol 273-276 ◽  
pp. 616-621
Author(s):  
Hikmet Ş. Aybar ◽  
Mohsen Sharifpur
Keyword(s):  
Two Phase Flow ◽  
Fluid Model ◽  
Three Dimensional ◽  
Phase Flow ◽  
Governing Equations ◽  
Ensemble Averaging ◽  
Two Phase ◽  
Transfer Equations ◽  
Two Fluid Model ◽  
Two Fluid

Generation of vapor and predication of its behavior is an important problem in many industries. In this study, the three dimensional governing equations for turbulence two-phase flow are derived using ensemble averaging two fluid model. The governing equations are simplified by a heuristic approach based on boiling data, and the equations are used to obtain the parameters for each phase along the channel. A computer program is written for the simplified one-dimensional equations, and the results are compared with experimental data.

Analysis of Two-Phase Cavitating Flow with Two-Fluid Model Using Integrated Boltzmann Equations

2013 ◽  
Vol 5 (05) ◽  
pp. 607-638 ◽  
Author(s):  
Shuhong Liu ◽  
Yulin Wu ◽  
Yu Xu ◽  
Hua-Shu Dou
Keyword(s):  
Turbulence Model ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Three Dimensional ◽  
Cavitating Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Pump Sump ◽  
Two Fluid Model ◽  
Two Fluid

AbstractIn the present work, both computational and experimental methods are employed to study the two-phase flow occurring in a model pump sump. The two-fluid model of the two-phase flow has been applied to the simulation of the three-dimensional cavitating flow. The governing equations of the two-phase cavitating flow are derived from the kinetic theory based on the Boltzmann equation. The isotropic RNGk — ε — kcaturbulence model of two-phase flows in the form of cavity number instead of the form of cavity phase volume fraction is developed. The RNGk—ε—kcaturbulence model, that is the RNGk — eturbulence model for the liquid phase combined with thekcamodel for the cavity phase, is employed to close the governing turbulent equations of the two-phase flow. The computation of the cavitating flow through a model pump sump has been carried out with this model in three-dimensional spaces. The calculated results have been compared with the data of the PIV experiment. Good qualitative agreement has been achieved which exhibits the reliability of the numerical simulation model.

Simplified two-group two-fluid model for three-dimensional two-phase flow Computational Fluid Dynamics for vertical upward flow

2018 ◽  
Vol 108 ◽  
pp. 503-516 ◽  
Author(s):  
Takashi Hibiki ◽  
Joshua P. Schlegel ◽  
Tetsuhiro Ozaki ◽  
Shuichiro Miwa ◽  
Somboon Rassame
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Three Dimensional ◽  
Phase Flow ◽  
Upward Flow ◽  
Two Phase ◽  
Two Fluid Model ◽  
Two Fluid
Sign in / Sign up

Export Citation Format

Share Document