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Computational Investigation of Buoyancy Influenced Flows and Benchmarking exercise

7th Int. ERCOFTAC Symposium -ETMM7- 4-6 June 2008,Limassol, Cyprus. Computational Investigation of Buoyancy Influenced Flows and Benchmarking exercise Presenter: Yacine Addad (PDRA) (KNOO Team: D. Laurence, M. Cotton, A. Keshmiri, S. Rolfo)

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Computational Investigation of Buoyancy Influenced Flows and Benchmarking exercise

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  1. 7th Int. ERCOFTAC Symposium-ETMM7- 4-6 June 2008,Limassol, Cyprus Computational Investigation of Buoyancy Influenced Flows and Benchmarking exercise Presenter: Yacine Addad (PDRA) (KNOO Team: D. Laurence, M. Cotton, A. Keshmiri, S. Rolfo) (Collaborators: S. Benhamadouche, R. Howard, F. di Mare) School of Mechanical, Aerospace & Civil Engineering (MACE) The University of Manchester

  2. The Heated pipe: Relevance to AGR and VHTR AGR working scheme

  3. RANS models predictions buoyancy aiding

  4. Expt. of Polyakov & Shindin Results for Fully-Developed ForcedConvection. (no buoyancy)

  5. Buoyancy effects on turbulence in VHTR channels: WR-LES Test Case Description • Re=180 based on R and u. • Boussinesq Approximation. • Periodic Flow. • Lz=30R • Grid1: 1.61 million • Grid2: 4.83 million • Grid1 Resolution: r+min=1.0, +=6.28, z+=18. • Grid2 Resolution: r+min=1.0, +=6.28, z+=7.03.

  6. Nusselt number as a function of the buoyancy parameter Ratio of SGS to molecular viscosity from You et al. For RANS models predictions, see the paper by Amir Keshmiri et al.

  7. Buoyancy effects on turbulence in VHTR channels: WR-LES Case1: Forced convection Gr/Re2=0.0 Data normalized by the bulk velocity

  8. Buoyancy effects on turbulence in VHTR channels: WR-LES Cases from Gr/Re2=0.063 to Gr/Re2=0.241 Data normalized by the bulk velocity

  9. NEARLY-HORIZONTAL SHALLOW CAVITYTEST CASE Plan Y-Z 0.8h LES Grid (Case1) • Ra= 4.16108 • NCELL= 3 million • Boussinesq approximation • Pr=0.71 (Air) • =5°

  10. NEARLY-HORIZONTAL SHALLOW CAVITYTEST CASE LES RESULTS Q=0.05

  11. NEARLY-HORIZONTAL SHALLOW CAVITYTEST CASE LES RESULTS

  12. NEARLY-HORIZONTAL SHALLOW CAVITYTEST CASE • RANS RESULTS • Low-Re. models tested: • k- Lien et al. (1996) • k- Wilcox (1998) • k- SST Menter (1993) • v2-f Lien & Durbin (1996) • Buoyancy term • included in k-equation • thermal fluxes

  13. Energy conservation: Taylor-Green vortices test case.

  14. Taylor-Green vortices test case: mesh generation. Resolution: 60 x 60 Time step: 0.01 => CFLmax < 0.2

  15. Effects of the velocity/pressure coupling

  16. Comparison between the codes for RR=0.75 (6/8)‏ RR=0.75  6/8

  17. Channel flow test case • Re=395 • Domain 2 2  • LES Ncells= 443,272 • DNS Ncells = 9,486,336 • (Ref: Moser et al. 1999)

  18. Channel flow test case: Mean Velocity predictions

  19. Channel flow test case: Reynolds Stresses

  20. Budgets of the Reynolds stress components Ref: T. Omori et al. Int. J. Heat and fluid flow 2008

  21. Channel flow test case: Budget for k Dissipation term Viscus diffusion term

  22. STAR: Grid (141x184x177) = 4.59 million DNS : Grid (256x193x192)= 9.48 million Budget for k

  23. STAR: Grid (141x184x177) = 4.59 million DNS : Grid (256x193x192)= 9.48 million Budget for uu

  24. STAR: Grid (141x184x177) = 4.59 million DNS : Grid (256x193x192)= 9.48 million Budget for vv

  25. STAR: Grid (141x184x177) = 4.59 million DNS : Grid (256x193x192)= 9.48 million Budget for ww

  26. STAR: Grid (141x184x177) = 4.59 million DNS : Grid (256x193x192)= 9.48 million Budget for uv

  27. Conclusions Acknowledgements: TSEC programme 'KNOO' EPSRCfunding under grant EP/C549465/1 for PDRA and Computer resources

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