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

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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Interfacial Pressure Coefficient for Ellipsoids and Its Effect on the Two-Fluid Model Eigenvalues

Journal of Fluids Engineering ◽

10.1115/1.4032755 ◽

2016 ◽

Vol 138 (8) ◽

Cited By ~ 7

Author(s):

Avinash Vaidheeswaran ◽

Martin Lopez de Bertodano

Keyword(s):

Fluid Model ◽

Pressure Coefficient ◽

Well Posedness ◽

Virtual Mass ◽

Two Phase Flows ◽

Two Phase ◽

Pressure Coefficients ◽

Interfacial Pressure ◽

Two Fluid Model ◽

Two Fluid

Analytical expressions for interfacial pressure coefficients are obtained based on the geometry of the bubbles occurring in two-phase flows. It is known that the shape of the bubbles affects the virtual mass and interfacial pressure coefficients, which in turn determines the cutoff void fraction for the well-posedness of two-fluid model (TFM). The coefficient used in the interfacial pressure difference correlation is derived assuming potential flow around a perfect sphere. In reality, the bubbles seen in two-phase flows get deformed, and hence, it is required to estimate the coefficients for nonspherical geometries. Oblate and prolate ellipsoids are considered, and their respective coefficients are determined. It is seen that the well-posedness limit of the TFM is determined by the combination of virtual mass and interfacial pressure coefficient used. The effect of flow separation on the coefficient values is also analyzed.

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

Volume 1: Fora, Parts A, B, C, and D ◽

10.1115/fedsm2003-45557 ◽

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 < CL < 0.29.

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Numerical Simulation Analysis of Fluid in the Semi-State within the Desulphurization Tower

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.118-120.921 ◽

2010 ◽

Vol 118-120 ◽

pp. 921-924 ◽

Cited By ~ 1

Author(s):

Wei Lin Guo ◽

Chao He

Keyword(s):

Numerical Simulation ◽

Flow Field ◽

Circulating Fluidized Bed ◽

Simulation Analysis ◽

Fluid Model ◽

Simulation Design ◽

Tower Structure ◽

Two Fluid Model ◽

Major Equipment ◽

Two Fluid

In this paper, the flow field in the desulphurization tower is studied deeply based on two-fluid model, particle dynamics theory and FLUENT. A numerical simulation analysis of fluid within the desulphurization tower is done and the desulphurization tower is the major equipment in the system. The simulation design and calculations show that the two-fluid model is reasonable to analyze the flow field. The simulation results show that smoke can form good reaction environment within the desulphurization tower. It is meaningful for the further optimization of designing desulphurization tower structure in the circulating fluidized bed system.

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Numerical Investigation of the Effect of Bottom Shape on the Flow Field and Particle Suspension in a DTB Crystallizer

International Journal of Chemical Engineering ◽

10.1155/2016/6862152 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Hao Pan ◽

Jun Li ◽

Yang Jin ◽

Bo Yang ◽

Xing Li

Keyword(s):

Flow Field ◽

Volume Fraction ◽

Fluid Model ◽

Bottom Surface ◽

Particle Suspension ◽

Eulerian Model ◽

Surface Diameter ◽

Computational Fluid Dynamics Cfd ◽

Two Fluid Model ◽

Two Fluid

The influence of the bottom shape on the flow field distribution and particle suspension in a DTB crystallizer was investigated by Computational Fluid Dynamics (CFD) coupled with Two-Fluid Model (Eulerian model). Volume fractions of three sections were monitored on time, and effect on particle suspension could be obtained by analyzing the variation tendency of volume fraction. The results showed that the protruding part of aWtype bottom could make the eddies smaller, leading to the increase of velocity in the vortex. Modulating the detailed structure of theWtype bottom to make the bottom surface conform to the streamlines can reduce the loss of the kinetic energy of the flow fluid and obtain a larger flow velocity, which made it possible for the particles in the bottom to reach a better suspension state. Suitable shape parameters were also obtained; the concave and protruding surface diameter are 0.32 and 0.373 times of the cylindrical shell diameter, respectively. It is helpful to provide a theoretical guidance for optimization of DTB crystallizer.

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

Journal of Fluids Engineering ◽

10.1115/1.1777231 ◽

2004 ◽

Vol 126 (4) ◽

pp. 573-577 ◽

Cited By ~ 17

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.

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Solid-Liquid Slurry Flow Through an Expansion in a Rectangular Duct

Volume 4: Fluid-Structure Interaction ◽

10.1115/pvp2013-97247 ◽

2013 ◽

Author(s):

Gianandrea Vittorio Messa ◽

Stefano Malavasi

Keyword(s):

Flow Field ◽

Fluid Model ◽

Experimental Tests ◽

Sudden Expansion ◽

Horizontal Pipe ◽

Solids Concentration ◽

Two Fluid Model ◽

Liquid Slurry ◽

Solid Liquid ◽

Two Fluid

Duct flows of solid-liquid slurries are frequently encountered in many engineering applications. The literature about the behaviour of such mixtures in correspondence to hydraulic singularities — such as sudden variation of duct section, perforated plates and bar screens — is rather poor, despite they are integral part of the plants. The technical difficulties faced whilst performing experimental tests made CFD almost the only possible way to study the flow field in detail. In the present work the flow of sand-water mixtures through a sudden expansion in a rectangular horizontal duct is investigated by means of a two-fluid model. Due to the lack of experimental data available, a sensitivity analysis is performed to quantify the influence of the terms of the two-fluid model which proved negligible in the horizontal pipe case, topic of previous investigations. Computations were performed for either dilute or dense mixtures, in order to study the effect of the mean solids concentration on the flow field. Moreover, the effect of channel width is investigated to assess the validity of the hypothesis of two-dimensionality of the flow.

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