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Title: Assessing the capability of continuum and discrete particle methods to simulate gas-solids flow using DNS predictions as a benchmark

For this study, gas–solids flow in a three-dimension periodic domain was numerically investigated by direct numerical simulation (DNS), computational fluid dynamic-discrete element method (CFD-DEM) and two-fluid model (TFM). DNS data obtained by finely resolving the flow around every particle are used as a benchmark to assess the validity of coarser DEM and TFM approaches. The CFD-DEM predicts the correct cluster size distribution and under-predicts the macro-scale slip velocity even with a grid size as small as twice the particle diameter. The TFM approach predicts larger cluster size and lower slip velocity with a homogeneous drag correlation. Although the slip velocity can be matched by a simple modification to the drag model, the predicted voidage distribution is still different from DNS: Both CFD-DEM and TFM over-predict the fraction of particles in dense regions and under-predict the fraction of particles in regions of intermediate void fractions. Also, the cluster aspect ratio of DNS is smaller than CFD-DEM and TFM. Since a simple correction to the drag model can predict a correct slip velocity, it is hopeful that drag corrections based on more elaborate theories that consider voidage gradient and particle fluctuations may be able to improve the current predictions of cluster distribution.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [1]
  1. National Energy Technology Lab. (NETL), Morgantown, WV (United States)
  2. Chinese Academy of Sciences (CAS), Beijing (China). State Key Lab. of Multiphase Complex Systems and Inst. of Process Engineering (IPE); Univ. of Chinese Academy of Sciences, Beijing (China)
  3. National Energy Technology Lab. (NETL), Morgantown, WV (United States); AECOM, Morgantown, WV (United States)
  4. Chinese Academy of Sciences (CAS), Beijing (China). State Key Lab. of Multiphase Complex Systems and Inst. of Process Engineering (IPE)
Publication Date:
Report Number(s):
NETL-PUB-21175
Journal ID: ISSN 0032-5910; PII: S0032591017306782
Grant/Contract Number:
91434201
Type:
Accepted Manuscript
Journal Name:
Powder Technology
Additional Journal Information:
Journal Volume: 321; Journal Issue: C; Journal ID: ISSN 0032-5910
Publisher:
Elsevier
Research Org:
National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States); Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE); National Natural Science Foundation of China (NNSFC)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 97 MATHEMATICS AND COMPUTING; Computational fluid dynamics; Discrete element method; Direct numerical simulation; Fluidized bed; Drag model; Two-fluid model
OSTI Identifier:
1440342