The Modeling of Lift and Dispersion Forces in Two-Fluid Model Simulations of a Bubbly Jet

2004 ◽  
Vol 126 (4) ◽  
pp. 573-577 ◽  
Author(s):  
M. Lopez de Bertodano ◽  
F. J. Moraga ◽  
D. A. Drew ◽  
R. T. Lahey,
Keyword(s):  
Fluid Model ◽  
Phase 1 ◽  
Lift Coefficient ◽  
Turbulent Dispersion ◽  
Dispersion Forces ◽  
Model Simulations ◽  
Diffusion Force ◽  
Bubbly Jet ◽  
Two Fluid Model ◽  
Two Fluid

Two-fluid model simulations of a bubbly vertical jet are presented. The purpose of these simulations is to assess the modeling of lift and turbulent dispersion forces in a free shear flow. The turbulent dispersion models used herein are based on the application of a kinetic transport equation, similar to Boltzmann’s equation, to obtain the turbulent diffusion force for the dispersed phase [1–4]. They have already been constituted and validated for the case of particles in homogeneous turbulence and jets [5] and for microscopic bubbles in grid generated turbulence and mixing layers [6,7]. It was found that it is possible to simulate the experimental data of Sun [8] (see Figs. 1–6) for a bubbly jet with 1 mm diameter bubbles. Good agreement is obtained using the model of Brucato et al. [9] for the modulation of the drag force by the liquid phase turbulence and a constant lift coefficient, CL. However, little sensitivity is observed to the value of the lift coefficient in the range 0<CL<0.29.

The Modeling of Lift and Dispersion Forces in Two-Fluid Model Simulations: Part I — Jet Flows

2003 ◽  
Author(s):  
M. Lopez de Bertodano ◽  
F. J. Moraga ◽  
D. A. Drew ◽  
R. T. Lahey
Keyword(s):  
Fluid Model ◽  
Phase 1 ◽  
Lift Coefficient ◽  
Turbulent Dispersion ◽  
Jet Flows ◽  
Dispersion Forces ◽  
Model Simulations ◽  
Turbulence Dispersion ◽  
Two Fluid Model ◽  
Two Fluid

Two-fluid model simulations of a bubbly vertical jet are presented. The purpose of these simulations is to assess the modeling of turbulence dispersion and lift forces in a free shear flow. Although turbulence dispersion forces have previously been validated using simpler canonical flows and microscopic particles or bubbles, there was a need to asses the model performance for larger bubbles in more turbulent flows. This method, of validating two-fluid models in flows of increasing complexity has the advantage of excluding, or at least minimizing, the possibility of cancellation of errors when modeling several forces. In a companion paper (see Part-II), the present two-fluid model is extended to a boundary layer in which forces induced by the presence of a wall are important. The turbulent dispersion models used herein are based on the application of a kinetic transport equation, similar to Boltzmann’s equation, to obtain the turbulent diffusion force for the dispersed phase [1, 2]. They have already been constituted and validated for the case of particles in homogeneous turbulence and jets [3] and for microscopic bubbles in grid generated turbulence and mixing layers [4]. It was found that it is possible to simulate the experimental data in Ref. [5] (See Figures-1 to 4) for a bubbly jet with 1 mm diameter bubbles. Good agreement is obtained using the model of Brucato et al. [7] for the modulation of the drag force by the liquid phase turbulence and a constant lift coefficient, CL. However, little sensitivity is observed to the value of the lift coefficient in the range 0 &lt; CL &lt; 0.29.

Prediction of Parameters Distribution of Upward Boiling Two-Phase Flow With Two-Fluid Models

2002 ◽  
Author(s):  
Wei Yao ◽  
Christophe Morel
Keyword(s):  
Void Fraction ◽  
Fluid Model ◽  
Constitutive Relations ◽  
Turbulent Dispersion ◽  
Dispersion Force ◽  
Liquid Temperature ◽  
Two Phase ◽  
Radial Profiles ◽  
Two Fluid Model ◽  
Two Fluid

In this paper, a multidimensional two-fluid model with additional turbulence k–ε equations is used to predict the two-phase parameters distribution in freon R12 boiling flow. The 3D module of the CATHARE code is used for numerical calculation. The DEBORA experiment has been chosen to evaluate our models. The radial profiles of the outlet parameters were measured by means of an optical probe. The comparison of the radial profiles of void fraction, liquid temperature, gas velocity and volumetric interfacial area at the end of the heated section shows that the multidimensional two-fluid model with proper constitutive relations can yield reasonably predicted results in boiling conditions. Sensitivity tests show that the turbulent dispersion force, which involves the void fraction gradient, plays an important role in determining the void fraction distribution; and the turbulence eddy viscosity is a significant factor to influence the liquid temperature distribution.

Two-Fluid Model Simulations of the National Energy Technology Laboratory Bubbling Fluidized Bed Challenge Problem

2016 ◽  
Vol 55 (17) ◽  
pp. 5063-5077 ◽  
Author(s):  
Musango Lungu ◽  
Haotong Wang ◽  
Jingdai Wang ◽  
Yongrong Yang ◽  
Fengqiu Chen
Keyword(s):  
Fluidized Bed ◽  
Fluid Model ◽  
Energy Technology ◽  
Model Simulations ◽  
Bubbling Fluidized Bed ◽  
Two Fluid Model ◽  
Two Fluid

Modeling of Low and High Void Fraction Two-Phase Flow in a Vertical Pipe by Using the Two-Fluid Model

2018 ◽  
Author(s):  
Shimo Yu ◽  
Xiao Yan ◽  
Junyi Zhang
Keyword(s):  
Void Fraction ◽  
Radial Distribution ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Turbulent Dispersion ◽  
Test Facility ◽  
Phase Flow ◽  
Two Phase ◽  
Two Fluid Model ◽  
Two Fluid

Two-phase flow is an important and common phenomenon in nuclear reactor systems, and the characteristics of two-phase flow such as heat transfer and pressure drop strongly depend on the radial distribution of void fraction. This paper is presenting the CFD simulation for void fraction radial distribution of mono- and poly-disperse air-water two phase flow using Euler-Euler two-fluid model. Interfacial forces including transverse forces such as lift, wall and turbulent dispersion forces are taken into account, Furthermore the bubble size distribution and bubble break-up and coalescence processes are taken into account in case of a poly-disperse flow by using the S-Gamma model. The sauter mean diameter and interfacial area concentration (IAC) distribution can also be obtained. The simulation results are compared to an experimental database of MT-LOOP test facility (FZD, Germany)[1].

scholarly journals Use of α -shapes for the measurement of 3D bubbles in fluidized beds from two-fluid model simulations

2016 ◽  
Vol 288 ◽  
pp. 409-421 ◽  
Author(s):  
Ignacio Julián ◽  
David González ◽  
Javier Herguido ◽  
Miguel Menéndez
Keyword(s):  
Fluidized Beds ◽  
Fluid Model ◽  
Model Simulations ◽  
Two Fluid Model ◽  
Two Fluid

Evaluation on the Application of Two-Fluid Multiphase Model to Supercavity

2013 ◽  
Vol 275-277 ◽  
pp. 417-428
Author(s):  
Jing Jun Zhou ◽  
Chun Peng Dong ◽  
Qing Rui Xiang
Keyword(s):  
Flow Field ◽  
Fluid Model ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Multiphase Model ◽  
Structure Of Flow ◽  
Natural Cavitation ◽  
Two Fluid Model ◽  
Ventilated Supercavity ◽  
Two Fluid

The lubrication of external liquid with supercavity has been the goals of specialists for many years. Either ventilated cavity or natural cavity is firstly related to multiphase flow. In this paper, in order to quantitatively predict the cavitating flow especially the ventilated supercavity and understand the structure of flow field in the cavity, two kinds of multiphase model including the homogeneous flow model and the two-fluid model were adopted separately. Besides, SST and DES turbulence model are used for steady and unsteady simulations. By comparing the simulating results with experimental results in water tunnel, the two-fluid model was proved to have the high accuracy in predicting the ventilated supercavity including the cavity shape and lift coefficient of the vehicle. On the other hand, for natural cavitation, the mixture model and the two-fluid model have little difference in predicting the pressure coefficient, however, the two-fluid model can give more detailed flow field.

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