Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure

The fixed pivot method can only conserve two moments while other moments suffer from inherent errors caused by internal inconsistency. In this work, we present a comprehensive investigation regarding the influence of moment closure on population balance and hydrodynamics in the coupled CFD-PBM simul...

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Main Authors: Shang, Xiaopeng, Ng, Bing Feng, Wan, Man Pun, Ding, Shirun
Other Authors: School of Mechanical and Aerospace Engineering
Format: Article
Language:English
Published: 2019
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Online Access:https://hdl.handle.net/10356/83242
http://hdl.handle.net/10220/50136
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-832422023-03-04T17:23:14Z Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure Shang, Xiaopeng Ng, Bing Feng Wan, Man Pun Ding, Shirun School of Mechanical and Aerospace Engineering Population Balance Modeling Engineering Engineering::Mechanical engineering The fixed pivot method can only conserve two moments while other moments suffer from inherent errors caused by internal inconsistency. In this work, we present a comprehensive investigation regarding the influence of moment closure on population balance and hydrodynamics in the coupled CFD-PBM simulations. The CFD-PBM model, which conserves the surface area and volume (second and third moment, i.e. CFD-PBM-SV model), and the number and volume (zeroth and third moment, i.e. CFD-PBM-NV model), has been developed based on a two-fluid model. To assess the accuracy of Sauter Mean Diameter (SMD) with different moment closures, a transient and homogeneous case is first simulated by the single PBM model, which conserves the surface area-volume (i.e. PBM-SV model) and number-volume (i.e. PBM-NV model), respectively. It shows that in comparison with the analytical solution, the SMD predicted by the PBM-SV model shows higher accuracy than the PBM-NV model with identical sectioning resolution, and the PBM-NV model can give satisfactory results only on very fine sectioning grids. A rectangular bubble column is then simulated by the CFD-PBM-SV and CFD-PBM-NV model, respectively. It is found that both models can capture the oscillating bubble plume of the gas-liquid flow inside the column reactor. The flow features predicted by the CFD-PBM-SV model show better agreement with experimental data, in terms of the time-averaged vertical liquid velocity, gas hold-up and plume oscillation period, than the CFD-PBM-NV model. It is speculated that the better performance of the CFD-PBM-SV model is ascribed to more accurate predictions of interfacial forces and momentum transfer between the two phases due to internal consistency of the local SMD compared to the CFD-PBM-NV model. Accepted version 2019-10-10T07:50:28Z 2019-12-06T15:18:12Z 2019-10-10T07:50:28Z 2019-12-06T15:18:12Z 2019 Journal Article Shang, X., Ng, B. F., Wan, M. P., & Ding, S. (2019). Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure. Chemical Engineering Journal, 122882-. doi:10.1016/j.cej.2019.122882 1385-8947 https://hdl.handle.net/10356/83242 http://hdl.handle.net/10220/50136 10.1016/j.cej.2019.122882 en Chemical Engineering Journal © 2019 Elsevier. All rights reserved. This paper was published in Chemical Engineering Journal and is made available with permission of Elsevier. 56 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Population Balance Modeling
Engineering
Engineering::Mechanical engineering
spellingShingle Population Balance Modeling
Engineering
Engineering::Mechanical engineering
Shang, Xiaopeng
Ng, Bing Feng
Wan, Man Pun
Ding, Shirun
Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure
description The fixed pivot method can only conserve two moments while other moments suffer from inherent errors caused by internal inconsistency. In this work, we present a comprehensive investigation regarding the influence of moment closure on population balance and hydrodynamics in the coupled CFD-PBM simulations. The CFD-PBM model, which conserves the surface area and volume (second and third moment, i.e. CFD-PBM-SV model), and the number and volume (zeroth and third moment, i.e. CFD-PBM-NV model), has been developed based on a two-fluid model. To assess the accuracy of Sauter Mean Diameter (SMD) with different moment closures, a transient and homogeneous case is first simulated by the single PBM model, which conserves the surface area-volume (i.e. PBM-SV model) and number-volume (i.e. PBM-NV model), respectively. It shows that in comparison with the analytical solution, the SMD predicted by the PBM-SV model shows higher accuracy than the PBM-NV model with identical sectioning resolution, and the PBM-NV model can give satisfactory results only on very fine sectioning grids. A rectangular bubble column is then simulated by the CFD-PBM-SV and CFD-PBM-NV model, respectively. It is found that both models can capture the oscillating bubble plume of the gas-liquid flow inside the column reactor. The flow features predicted by the CFD-PBM-SV model show better agreement with experimental data, in terms of the time-averaged vertical liquid velocity, gas hold-up and plume oscillation period, than the CFD-PBM-NV model. It is speculated that the better performance of the CFD-PBM-SV model is ascribed to more accurate predictions of interfacial forces and momentum transfer between the two phases due to internal consistency of the local SMD compared to the CFD-PBM-NV model.
author2 School of Mechanical and Aerospace Engineering
author_facet School of Mechanical and Aerospace Engineering
Shang, Xiaopeng
Ng, Bing Feng
Wan, Man Pun
Ding, Shirun
format Article
author Shang, Xiaopeng
Ng, Bing Feng
Wan, Man Pun
Ding, Shirun
author_sort Shang, Xiaopeng
title Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure
title_short Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure
title_full Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure
title_fullStr Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure
title_full_unstemmed Investigation of CFD-PBM simulations based on fixed pivot method : influence of the moment closure
title_sort investigation of cfd-pbm simulations based on fixed pivot method : influence of the moment closure
publishDate 2019
url https://hdl.handle.net/10356/83242
http://hdl.handle.net/10220/50136
_version_ 1759856396171476992