CFD predictions for flow‐regime transitions in bubble columns

Monahan, Sarah M.; Vitankar, Vivek; Fox, Rodney O.

doi:10.1002/aic.10425

Cited by 102 publications

(69 citation statements)

References 81 publications

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“…55,56 The full description of the two-fluid model can be found in our previous work, [50][51][52] and a brief review of the notable terms is given below. Subscripts c and d refer to the continuous phase (water) and the dispersed phase (air), respectively, while R, F, and u represent volume fraction, density, and velocity, respectively.…”

Section: Review Of Model Formulationmentioning

confidence: 99%

“…[47][48][49] This disagreement between theory and experiments suggests that important physics is missing in the various twofluid models used to model bubble columns. For example, the numerical studies presented in our previous work [50][51][52][53] showed that predictions for flow regimes and flow-transition regions in air-water bubble columns are highly dependent on the momentum-transfer model formulation, which includes drag, virtual-mass, lift, rotation, and strain forces, and Sato's 54 bubbleinduced turbulence (BIT) model. Applying all interphase force models with a particular set of model parameters agreed qualitatively with the experiments of Harteveld et al 47,48 (hereafter referred to as the "Delft experiments"), including the observed transition to heterogeneous flow at high gas holdup.…”

Section: Introductionmentioning

confidence: 99%

“…Our detailed literature survey 50 has shown that all the interphase force terms, with the exception of the rotation and strain terms, have been used in other studies reported in the literature. Note that any of the force models can be removed from the analysis by setting the corresponding model coefficient equal to zero.…”

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confidence: 99%

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Validation of Two-Fluid Simulations of a Pseudo-Two-Dimensional Bubble Column with Uniform and Nonuniform Aeration

Monahan

Fox

2009

Ind. Eng. Chem. Res.

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The multiphase flow simulated in this work corresponds to the pseudo-2D bubble-column experiments at Delft University of Technology (Harteveld et al. Can. J. Chem. Eng. 2003, 81, 389-394). As in the work of Monahan and Fox (AIChE J. 2007, 53, 9-18), the complete set of interphase force models includes drag, added-mass, lift, rotation, and strain. The simulation results are presented in the form of comparisons with the experimental data for the time-averaged gas holdup and the instantaneous and time-averaged air and liquid velocity fields. Overall, the qualitative and quantitative comparisons between experiments and simulations are satisfactory for both uniform and nonuniform aeration. In particular, the model predicts the flow patterns observed in the experiments, but in some cases at slightly different values of the amount of aeration. In the latter cases, it is shown that changing the model parameters does not improve the agreement with experiments. However, changing the liquid-velocity boundary condition from zero stress to zero slip leads to a small improvement. The multiphase flow simulated in this work corresponds to the pseudo-2D bubble-column experiments at Delft University of Technology (Harteveld et al. Can. J. Chem. Eng. 2003, 81, 389-394). As in the work of Monahan and Fox (AIChE J. 2007, 53, 9-18), the complete set of interphase force models includes drag, added-mass, lift, rotation, and strain. The simulation results are presented in the form of comparisons with the experimental data for the time-averaged gas holdup and the instantaneous and time-averaged air and liquid velocity fields. Overall, the qualitative and quantitative comparisons between experiments and simulations are satisfactory for both uniform and nonuniform aeration. In particular, the model predicts the flow patterns observed in the experiments, but in some cases at slightly different values of the amount of aeration. In the latter cases, it is shown that changing the model parameters does not improve the agreement with experiments. However, changing the liquid-velocity boundary condition from zero stress to zero slip leads to a small improvement. Disciplines Biological Engineering | Chemical Engineering

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Section: Review Of Model Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Validation of Two-Fluid Simulations of a Pseudo-Two-Dimensional Bubble Column with Uniform and Nonuniform Aeration

Monahan

Fox

2009

Ind. Eng. Chem. Res.

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“…Zhu et al [28] modeled 3D gas flows through Euler-Euler CFD simulation. Despite 3D models [29,30] were more precise than 2D ones [31,32], 2D models could still provide enough information and save time tremendously. Thus, in the case of the flow regime was not complex, a 2D model could be used to understand expecting results [33].…”

Section: Introductionmentioning

confidence: 99%

A Two-Phase Model of Air Shock Wave Induced by Rock-Fall in Closed Goaf

Ren

Cao

et al. 2017

Preprint

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“…Numerical simulations of bubble columns either employing Eulerian-Eulerian models [ [1][2][3][4][5], Euleri an-Lagrang ian mode ls [6][7][8] , or Volume of Fluid (VOF) [9] methods were surveyed. The Eulerian-Eulerian model treats di spersed (gas bubb les) and continuous (liquid) phases as interpenetrating continua, and describes the motion for gas and liquid phases Ill an Eulenan frame of reference.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of Gas-Liquid Flow Dynamics in Bubble Columns

2006

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There is great potential for using computational fluid dynamics (CFD) as a tool in scale-up and design of bubble columns. Full-scale experimentation in bubble columns is expensive and CFD is an alternative approach to study bubble column hydrodynamics. However, CFD can be computationally intensive as a predictive tool for a full three-dimensional geometry. In this paper, a 0.2 m diameter semi-batch bubble column is numerically simulated and the results are compared to experimental measurements performed by Rampure et al. [1]. The objectives are to examine and determine an appropriate set of numerical parameters and to determine if two-dimensional simulations are able to accurately predict observed bubble phenomena so that the computational cost can be reduced. A two-fluid Eulerian-Eulerian model is employed to represent each phase as interpenetrating continua and the conservation equations for mass and momentum for each phase are ensemble-averaged. Time-averaged gas holdup is mainly examined due to its significant role in gasliquid mass transfer and to compare to available data. Numerical predictions are presented for gas holdup at various axial heights as a function of radial position for a superficial gas velocity of 0.1 m/s. The numerical predictions exhibit the axial development of the gas holdup profile phenomena; that is, the gas holdup at the center of the column increases with increasing axial height. The effects of grid resolution and convergence criteria on the numerical predictions are also demonstrated. However, FD ca n be computationally inten ive a a predict ive too l fo r a full th reedimensional geo metry. In th i paper, a 0.2 m diameter semibatch bubble column is numerica ll y imul ated and the res ults are compared to ex perimental meas urements performed by R ampure et al. [ !] . The objecti ve are to exa mine and determine an appropriate set of numerica l parameters and to determine if two-dimensional simul ations are abl e to accuratel y predtct observed bubble phenomena so that the computational cost can be reduced. A two-fluid Euleri an-Eul eri an model is employed to represent each phase as interpenetrating continua and the conservation equations fo r mass and momentum for each phase are ensemble-averaged. Time-averaged gas holdup ts mamly examined due to its significant role in gas-liquid mass transfer and to compare to available data. Numerical predictions are presented for gas holdup at various ax ial heights as a function of radial position for a superfi cial gas velocity of ~· 1 mls. The numerical predictions exhibit the axial evelopment of the gas holdup profile phenomena · that is the gas h ld ' '. 0 up at the center of the column increases with Increasing axial height. The effects of grid resolution and convergence .t . d en ena on the numerical predictions are also emonstrated.

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CFD predictions for flow‐regime transitions in bubble columns

Cited by 102 publications

References 81 publications

Validation of Two-Fluid Simulations of a Pseudo-Two-Dimensional Bubble Column with Uniform and Nonuniform Aeration

Validation of Two-Fluid Simulations of a Pseudo-Two-Dimensional Bubble Column with Uniform and Nonuniform Aeration

A Two-Phase Model of Air Shock Wave Induced by Rock-Fall in Closed Goaf

Numerical Simulations of Gas-Liquid Flow Dynamics in Bubble Columns

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