Numerical Investigation of Mixed Convection in AGRs By By Amir Keshmiri Amir Keshmiri Supervisors: Supervisors: Prof. Dominique Laurence and Dr. Mark Cotton Prof. Dominique Laurence and Dr. Mark Cotton School of Mechanical, Aerospace & Civil Engineering (MACE) School of Mechanical, Aerospace & Civil Engineering (MACE) The University of Manchester The University of Manchester Internal Seminar at the University of Manchester – 07/11/2007 Internal Seminar at the University of Manchester – 07/11/2007
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Numerical Investigation of Mixed Convection in AGRs By Amir Keshmiri
Internal Seminar at the University of Manchester – 07/11/2007. Numerical Investigation of Mixed Convection in AGRs By Amir Keshmiri Supervisors: Prof. Dominique Laurence and Dr. Mark Cotton School of Mechanical, Aerospace & Civil Engineering (MACE) The University of Manchester. Outline. - PowerPoint PPT Presentation
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Numerical Investigation of
Mixed Convection in AGRs
ByBy
Amir KeshmiriAmir Keshmiri
Supervisors:Supervisors: Prof. Dominique Laurence and Dr. Mark Cotton Prof. Dominique Laurence and Dr. Mark Cotton
School of Mechanical, Aerospace & Civil Engineering (MACE)School of Mechanical, Aerospace & Civil Engineering (MACE)
The University of ManchesterThe University of Manchester
Internal Seminar at the University of Manchester – 07/11/2007Internal Seminar at the University of Manchester – 07/11/2007
Budgets of Turbulent Kinetic EnergyBudgets of Turbulent Kinetic Energy
Gr/Re^2=0.087Gr/Re^2=0.087Gr/Re^2=0.0Gr/Re^2=0.0
Heat Transfer Enhancement/ImpairmentHeat Transfer Enhancement/Impairment
Heat Transfer Enhancement/ImpairmentHeat Transfer Enhancement/Impairment
Heat Transfer Enhancement/ImpairmentHeat Transfer Enhancement/Impairment
Nu and Cf DevelopmentsNu and Cf Developments
Nu and Cf DevelopmentsNu and Cf Developments
Effects of Reynolds NumberEffects of Reynolds Number
Effects of Reynolds NumberEffects of Reynolds Number
ConclusionsConclusions
• Mixed convection in an ascending flow in a heated pipe, is a very complex phenomenon, despite its simplicity; Thus requires more research.
• Most of the turbulence models successfully predict the flow field at relatively low heat loading i.e. small Gr/Re^2
• Only very few turbulence models (only Linear k-ε) can predict the Re-laminarization Phenomena.
• There is a close agreement between the results of Code_Saturne and STAR-CD for the tested models.
• The relatively more advanced turbulence models, such as Non-Linear k- of Suga and V2f models are observed to suffer from convergence problems at high Gr/Re^2.
• The few available DNS data are not sufficient to carry out in depth validation of the RANS models, particularly at the maximum heat transfer impairment point.
• Development of Code_Saturne by implementing some advanced wall functions such as Analytical and Numerical Wall Functions.
• Cross examination of Code_Saturne with TEAM and STREAM Codes.
• Testing more complex geometries such as rib roughened surfaces, etc.
Future WorkFuture Work
AcknowledgementsAcknowledgements
This work was carried out as part of the TSEC programme KNOO and as such we are grateful
to the EPSRC for funding under grant EP/C549465/1
ReferencesReferences
[1] Launder, B.E. and Sharma, B.I., 1974, “Application of the energy dissipation model of turbulence to the calculation of flow near a spinning disc”, Lett. Heat Mass Transfer, 1, pp. 131-138.
[2] Cotton, M.A., Ismael, J.O., 1998, “A strain parameter turbulence model and its application to homogeneous and thin shear flows”, Int. J. Heat Fluid Flow 19, pp. 326–337.
[3] Craft, T.J., Launder, B.E. and Suga, K. 1996, “Development and application of a cubic eddy-viscosity model of turbulence”, Int. J. Heat Fluid Flow, 17, pp. 108-115
[4] You, J., Yoo, J.Y. and Choi. H., 2003, “Direct Numerical Simulation of Heated Vertical Air Flows in Fully Developed Turbulent Mixed Convection”, Int. J. Heat Mass Transfer, 46, pp.1613-1627
[5] Kim, W.S., Jackson, J.D. and He, S. (2006), “Computational Investigation into Buoyancy-Aided Turbulent Flow and Heat Transfer to Air in a Vertical Tube”, Turbulence, Heat and Mass Transfer, 5, (Hanjalić, K., Nagano, Y. and Jakirlic, S. (Editors))