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Numerical Investigation of Turbulent Fluid Flow and Heat Transfer in Complex Ducts

Rokni, Masoud LU (1998)
Abstract (Swedish)
Popular Abstract in Swedish

Numeriska methoder har används för att beräkna turbulent strömning och värmeöverföring i komplexa kanaler med olika turbulens modeller.
Abstract
Th need for a reliable and reasonable accurate turbulence model without specific convergence problem for calculating duct flows in industrial applications has become more evident. In this study a general computational method has been developed for calculating turbulent quantities in any arbitrary three dimensional duct. Four different turbulence models for predicting the turbulent Reynolds stresses namely; standard k-e model, the non-linear k-e model of Speziale, an Explicit Algebraic Stress Model (EASM) and a full Reynolds Stress Model (RSM) are compared with each other. The advantages, disadvantages and accuracy of these models are discussed. The turbulent heat fluxes are modeled by the SED concept, the GGDH and the WET methods. The... (More)
Th need for a reliable and reasonable accurate turbulence model without specific convergence problem for calculating duct flows in industrial applications has become more evident. In this study a general computational method has been developed for calculating turbulent quantities in any arbitrary three dimensional duct. Four different turbulence models for predicting the turbulent Reynolds stresses namely; standard k-e model, the non-linear k-e model of Speziale, an Explicit Algebraic Stress Model (EASM) and a full Reynolds Stress Model (RSM) are compared with each other. The advantages, disadvantages and accuracy of these models are discussed. The turbulent heat fluxes are modeled by the SED concept, the GGDH and the WET methods. The advantages of GGDH and WET compared to SED are discussed and the limitations of these models are clarified. The two-equation model of temperature invariance and its dissipation rate for calculating turbulent heat fluxes are also discussed. The low Reynolds number version of all the models are considered except for the RSM. At high Reynolds numbers the wall functions for both the temperature field and the flow field are applied. It has been shown that the standard k-e model with the curvilinear transformation provides false secondary motions in general non-orthogonal ducts and can not be used for predicting the turbulent secondar motions in ducts. The numerical method is based on the finite volume technique with non-staggered grid arrangement. The SIMPLEC algorithm is used for pressure-velocity coupling. A modified SIP and TDMA solving methods are implemented for solving the equations. The van Leer, QUICK and hybrid schemes are applied for treating the convective terms. However, in order to achieve stability in the k and e equations, the hybrid scheme is used for the convective terms in these equations. Periodic boundary conditions are imposed in the main flow direction for decreasing the number of grid points in this direction. In practical applications, periodic conditions in the main flow direction are commonly justified, since in wavy or corrugated ducts such conditions occur naturally. (Less)
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author
opponent
  • Prof. Collins, Micheal W., Thermo-Fluids Engineering Research Centre, City University, UK
organization
publishing date
type
Thesis
publication status
published
subject
keywords
SED, WET, GGDH, RNG, RSM, EASM, Low-Reynolds, Non-linear k-e, Heat transfer, Turbulent, Complex ducts, Secondary flows, Temperature invariance, Energy research, Energiforskning
pages
204 pages
publisher
Division of Heat Transfer, Lund Institute of Technology
defense location
Ole Römers väg 1, House of Mechanical Eng. M:B
defense date
1998-02-26 10:15
external identifiers
  • other:ISRN: LUTMDN/TMHT -- 1002 -- SE
ISSN
1104-7747
language
English
LU publication?
yes
id
abac246b-b6aa-45f1-88eb-fe0aececaf5b (old id 38433)
date added to LUP
2007-08-01 10:58:56
date last changed
2016-09-19 08:44:52
@phdthesis{abac246b-b6aa-45f1-88eb-fe0aececaf5b,
  abstract     = {Th need for a reliable and reasonable accurate turbulence model without specific convergence problem for calculating duct flows in industrial applications has become more evident. In this study a general computational method has been developed for calculating turbulent quantities in any arbitrary three dimensional duct. Four different turbulence models for predicting the turbulent Reynolds stresses namely; standard k-e model, the non-linear k-e model of Speziale, an Explicit Algebraic Stress Model (EASM) and a full Reynolds Stress Model (RSM) are compared with each other. The advantages, disadvantages and accuracy of these models are discussed. The turbulent heat fluxes are modeled by the SED concept, the GGDH and the WET methods. The advantages of GGDH and WET compared to SED are discussed and the limitations of these models are clarified. The two-equation model of temperature invariance and its dissipation rate for calculating turbulent heat fluxes are also discussed. The low Reynolds number version of all the models are considered except for the RSM. At high Reynolds numbers the wall functions for both the temperature field and the flow field are applied. It has been shown that the standard k-e model with the curvilinear transformation provides false secondary motions in general non-orthogonal ducts and can not be used for predicting the turbulent secondar motions in ducts. The numerical method is based on the finite volume technique with non-staggered grid arrangement. The SIMPLEC algorithm is used for pressure-velocity coupling. A modified SIP and TDMA solving methods are implemented for solving the equations. The van Leer, QUICK and hybrid schemes are applied for treating the convective terms. However, in order to achieve stability in the k and e equations, the hybrid scheme is used for the convective terms in these equations. Periodic boundary conditions are imposed in the main flow direction for decreasing the number of grid points in this direction. In practical applications, periodic conditions in the main flow direction are commonly justified, since in wavy or corrugated ducts such conditions occur naturally.},
  author       = {Rokni, Masoud},
  issn         = {1104-7747},
  keyword      = {SED,WET,GGDH,RNG,RSM,EASM,Low-Reynolds,Non-linear k-e,Heat transfer,Turbulent,Complex ducts,Secondary flows,Temperature invariance,Energy research,Energiforskning},
  language     = {eng},
  pages        = {204},
  publisher    = {Division of Heat Transfer, Lund Institute of Technology},
  school       = {Lund University},
  title        = {Numerical Investigation of Turbulent Fluid Flow and Heat Transfer in Complex Ducts},
  year         = {1998},
}