1 - UoM-EDF Wiki Collaborative Website : sample test cases.

1 - THMT 6, 2009 - H&FF Simulations for energies

UoM-EDF Wiki Collaborative Website : sample test cases


0.3

0.5

0.7

0.9

1.1

1.3

1.5

0.01 0.1 1 10Buoyancy Number

Nu

/Nu

0

Launder & Sharma Model (CONVERT)Cotton & Ismael Model (CONVERT)Suga Non-Linear Eddy Viscosity Model (CONVERT)Lien-Chen-Leschziner k-eps Model (STAR-CD)k-omega-SST Model (STAR-CD)Lien & Durbin v2f Model (STAR-CD)k-omega-SST Model (Code_Saturne)Manchester v2f Model (Code_Saturne)Large Eddy Simulation (STAR-CD)DNS - You et al (2003)

BENCHMARKING of codes: heated pipe

8.0425.34108

PrReD

DGrBo ehD

Nu ConvectionForcedatNuNu0


Heated vertical pipe test case

Temperature

Kinetic energy

- k- models miss relaminarisation- maybe too correlated to wall-distance (dominant effect of boundary condition, and further ref to “y” in SST version, - Consistent with poor transition predictions.

Ref: Keshmiri A., Addad Y. et al

www.saturne.cfdtm.org

http://www.saturne.cfdtm.org/


Models


Flow through in-line tube bundles

Mean pressure

gradient

Direction is in-lin

e

Large heat exchanger=> Homogeneous conditions

=> Periodic subset considered

Re=45 000, P/D= 1.5

Objectives: Flow induced vibrations in heat exchangers (Lift & Drag coef.)

Staggered: studied 10 years agoCurrent: in line

Embedded refinement


In-line tube bundle

[email protected], with STAR-CCM

- Fully symmetric conditions, but non-symmetric solutions

- Coanda effect ?

- Star-CCM LES launched to confirm EDF finding(Benhamadouche et al. NURETH 11, Avignon 2005)

Time averaged velocity field =>


Cross Flow in Tube Bundles

- 4 different gap ratios was tested. P/D=1.2, 1.5, 1.6 and 1.75

- Code Saturne and STAR CCM (I Afgan Thesis 07)

Average Cp comparison for P/D=1.5 case

Pseudo-average mean velocity streamlines. From left to right: P/D=1.2, P/D=1.5, P/D=1.6 and P/D=1.75

Average Velocity contours at mid section for P/D=1.5 case


Application to real Exchanger/ Steam Generator


Many occurrences of Swirling Flows: => Re Stress Transport model recommended


Figure 6: RSTM simulation of heterogeneities at the exit of a PWR upper plenum; scalar tracers through plenum to 4 hot leg exits (left); geometrical details as seen from actual mesh surface (right); secondary motion in hot leg cross section. (from JP Juhel and Martinez & Alvarez [17])

Flow exiting in upper leg: what does local probe measure?


Figure 7: Turbulent shear stress across a rotating channel ( from [18]).


Figure 8: “HYPI, FATHER” and “WATLON” T junction mixing test cases (top). Comparison of standard and advanced/”unsteady” wall functions for LES on the “WATLON” case [19]. Mean (left), rms (right) temperatures profiles and iso (centre); LES results by T. Pasutto [20].


Channel Flow LES on structured gridat Re*=395 (Re*=y+ at centre )

% error on friction

Under-Resolved LES

Under-resolved LES => more dangerous than coarse RANS !

=> Q-LES very much needed now that Industry is into LES


Kolmogorov lengthscale

Taylor microscale

Turbulent energy L (is model):

True or Integral L:

13 4

2

2

1

1

2f

u

ux

23k

Lturb

11 11 111 0

1, , ,

0, ,L x t R e r x t dr

R x t

Better knowledge of Length scales essential for LES


Integral length scales in channel flow

Turbulent energy scale is easy RANS “model” but does not represent true (2 point correlation) integral scale for channel flow

23k

Lturb

streaks

1- x : streamwise2- y : wall normal3 – z : spanwise

Solid: stream-wise separationDashed: span-wise separation

Nb: longitudinal lenghtscales are divided by 2


• ½ Million cells M, Re = 395, • “Wall resolved LES”• Complex geometry ?• Need Accurate precursor RANS

“Taylor scale” unstructured mesh Channel LES

Mean Velocity

y/d

2

2

1

1

2f

u

ux


Channel flow LES on “Taylor” mesh at Re = 395 :Reynolds Stresses


Budget for wall nomal velocity varianceSaturne & STAR Grids (141x184x177) = 4.59 millionDNS : Grid (256x193x192)= 9.48 million

Budget for vv (most difficult component)

Even DNS possible with codes design for industrial Applications


Proper meshing for LES tedious. Ex jet injection burner

Lenghtscale predicted by RANS : (k**3/2)/eps

Annular co-flow

Jet =>

Hand made grid very boring !Need for tools for adaptive meshing


- LES community very activeon this topic

- First idea reduce viscosity whenturbulent scale > cells

- OK for Detached Eddy Simulation (DES)- Not sufficient for turbulent structures to appear !

- Bad transition region (kink)where RANS viscosity is reduced but resolved structures are still too weak

Zonal modelling / RANS-LES coupling

Velocity profile Total Turb Shear stress

Overset RANS LES

Overlapping RANS - LES coupling

Re*=395 , 40x30x30 meshJ. Uribe, DESider Project

RANS contrib.

Resolved LES field contrib.

Run both RANS and LES simulation, overlapping2 Velocity fields, 2 viscosities, and blend only shear stress

LES

Re Cells395 40x30x30 59 39 26 158590 40x40x30 88 59 32 184

1100 50x50x40 140 88 46 2662000 50x50x40 256 160 83 4854000 64x80x64 400 200 99 574

Dx+ Dz+y+ @ f=0.5

y+ @ f=0.99

Reynolds number non-sensitivity

J. Uribe et al.


3. Besoins HPC


Figure 11: Evolution in computing power at EDF R&D, in Tflops (left). Code_Saturne performance on HPCx computer (Daresbury Lab. UK) for a channel flow LES (right).

6. Industrial Applications of Advanced Simulation in CFD to Tomorrow’s Energies

29 - Entité d'appartenance

HPC roadmap: application examples (founier Club U Sat 2008

2003 2010 201520072006

Consecutive to the Civaux thermal fatigue event

Computations enable to better understand the wall thermal loading in an injection.

Knowing the root causes of the event define a new design to avoid this problem.

Part of a fuel assembly3 grid assemblies

Computation with an L.E.S. approach for turbulent modelling

Refined mesh near the wall.

9 fuel assemblies

No experimental approach up to now

Will enable the study of side effects implied by the flow around neighbour fuel assemblies.

Better understanding of vibration phenomena and wear-out of the rods.

The whole vessel reactor

106 cells3.1013 operations

108 cells1016 operations




FujistuVPP 5000

1 of 4 vector processors

2 month length computation

Cluster, IBM Power5

400 processors

9 days

# 1 Gb of storage

2 Gb of memory

IBM Blue Gene/L « Frontier»

8000 processors

# 1 month

30 timesthe power of


# 1 month

# 15 Gb of storage

25 Gb of memory

# 10 Tb of storage

25 Tb of memory

# 1 Tb of storage

2,5 Tb of memory

# 200 Gb of storage

250 Gb of memory

Power of the computer Pre-processing not parallelized Pre-processing not parallelized

Mesh generation

… ibid. …

… ibid. …

Scalability / Solver

… ibid. …

… ibid. …

… ibid. …

Visualisation



# 1 month

2003 2010 201520072006

Consecutive to the Civaux thermal fatigue event

Computations enable to better understand the wall thermal loading in an injection.

Knowing the root causes of the event define a new design to avoid this problem.

Part of a fuel assembly3 grid assemblies

Computation with an L.E.S. approach for turbulent modelling

Refined mesh near the wall.

9 fuel assemblies

No experimental approach up to now

Will enable the study of side effects implied by the flow around neighbour fuel assemblies.

Better understanding of vibration phenomena and wear-out of the rods.

The whole vessel reactor











FujistuVPP 5000

1 of 4 vector processors

2 month length computation

Cluster, IBM Power5

400 processors

9 days

# 1 Gb of storage

2 Gb of memory


8000 processors

# 1 month



# 1 month

# 15 Gb of storage

25 Gb of memory

# 10 Tb of storage

25 Tb of memory

# 1 Tb of storage

2,5 Tb of memory

# 200 Gb of storage

250 Gb of memory

Power of the computer Pre-processing not parallelized Pre-processing not parallelized

Mesh generation

… ibid. …

… ibid. …

Scalability / Solver

… ibid. …

… ibid. …

… ibid. …

Visualisation



# 1 month


www.framatome-anp.com, www.westinghousenuclear.com

Ongoing: thermal hydraulics and vibrations of PWR fuel rods

Spacer & mixer grids: hold rods, increase heatTransfer and inter channel mixing.Pb: FIV, fretting

Code_SaturneLES

Turbulent excitation

Vibration

Code_Aster


Figure 12: (12.a) Geometry of the fuel assembly. (12.b) Mesh on the wall of the mixing grids. (12.c) 3D flow around fuel rods. (12.d) velocity intensity vortices around fuel rods in a horizontal plane.

Application n°1: Impact of mixing grids effects on the water flow in nuclear fuel rod assemblies


Figure 13: Computation of the temperature field of bolts holding the peripheral shielding in a nuclear core.

Application n°2: Mechanical behavior of screws of core shielding


Conclusions –LES in power generation industry

• LES of Industrial flow

• Much more information: Fluct. thermal stresses, fatigue, acoustics, FIV• Cost-wise accessible when limited to sub-domain (synthetic turbulence)• Complex geometry possibly easier than smooth channel flow

• Exploit better flexibility of professional/commercial software:

• Opens new range of applications for LES• More meshing control (total cell size control from pre-simulation) (Greater breakthrough than elaborate SGS models? )• High Re : RANS –LES coupling, embedded LES

• Cross-discipline research: Fluids / Structure-Mech/ Materials ?Cracks, Thermal stripping, ageing,

corrosion


Trust & Quality in LES serious issue:

- 99% LES are “post-dictions”, or “explanations”- how many failed LES / no. of published LES ? (ex. 2D Hill, Ahmed body..- errors can be much larger than in RANS - can we design next gen nuclear power plants using LES?

- mesh influence tremendous, but turbulence scales not known a priori- a posteriori quality criteria known (see Q-LES workshop B. Geurts) but trial and error most expensive with LES- do not venture outside pipe/channel flow applications?- or COLLABORATIVE work on validations in new areas on a large scale (i.e. reporting failures is very important)


References

1. Archambeau, F., Mechitoua, N. and Sakiz, M. A Finite Volume Method for the Computation of Turbulent Incompressible Flows – Industrial Applications, Int. J. Finite Volumes, Vol. 1. 2004.

2. Code_Saturne download URL: http://rd.edf.com/code_saturne (accessed 2009-05-11).3. Testcases DB: www.saturne.cfdtm.org and http://cfd.mace.manchester.ac.uk/ercoftac/4. Rupp I., Peniguel C., Tommy-Martin M. Large Scale Finite Element Thermal Analysis of Bolts of a

French PWR Core Internal Baffle Structure. 7th I. Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety NUTHOS-7, Seoul, Korea, Oct. 2008.

5. SYRTHES code download URL: http://rd.edf.com/syrthes (accessed 2009-05-11).6. FLOMANIA – A European Initiative on Flow Physics Modelling. Haase, Aupoix, Bunge, Swamborn

Eds. Notes on Numerical Fluid Mechanics Vol 94, Springer, 2006.7. ERCOFTAC Best Practice Guidelines for Industrial Computational Fluid Dynamics of Single

Phase Flows. V1.0, Jan 2000. URL: http://www.ercoftac.org/index.php?id=77).8. Best Practice Guidelines for the use of CFD in Nuclear Reactor Safety Applications. Report

NEA/CSNI/R(2007)5, 15 May 2007. Site: www.nea.fr/html/nsd/csni/cfd.htm URL: http://www.nea.fr/html/nsd/docs/2007/csni-r2007-5.pdf. (accessed 2009-05-11).

9. Keshmiri A., Addad Y., Cotton M.A., Laurence D. and Billard F. "Refined Eddy Viscosity Schemes and LES for Ascending Mixed Convection Flows" in Computational Heat Transfer (CHT08) Symp., Marakkech,11-16 May 2008, 1, pp. 274-279, 2008.

10. Durbin, P.A., Separated flow computations with the k-esp-v2 model. AIAA Journal, Vol.33(4), pp. 659-664, 1995.

11. Laurence D. R., Uribe J.C., Utyuzhnikov S.V., A Robust Formulation of the v2-f Model, J. Flow, Turbulence and Combustion, 73, 3-4, pp169-185, 2005.

12. Hanjalic, K., Popovac, M. Hadziabdic, M., A robust near- wall elliptic- relaxation eddy- viscosity model for CFD .I. J. Heat and Fluid Flow, 24, pp. 1047- 1051, 2004.

http://rd.edf.com/code_saturne

http://rd.edf.com/code_saturne

http://www.saturne.cfdtm.org/

http://rd.edf.com/syrthes

http://rd.edf.com/syrthes

http://www.ercoftac.org/index.php?id=77



http://www.nea.fr/html/nsd/csni/cfd.htm

http://www.nea.fr/html/nsd/docs/2007/csni-r2007-5.pdf


References-21. Manceau, R. An Improved Version of the Elliptic Blending Model. Application to Non-Rotating and

Rotating Channel Flows, in 4th Symp. Turb. Shear Flow Phenomena, J.A.C. Humphrey et al., eds., Williamsburg, Virginia, USA, pp. 259-264, 2005.

2. Manceau, R.,Wang, M., Laurence, D. Inhomogeneity and anisotropy effects on the redistribution term in RANS modeling. J. Fluid Mech., 438, pp. 307-338, 2001.

3. Benhamadouche S., Laurence D. LES, Coarse LES, and Transient RANS comparison on the flow across a tube bundle. I .J. of Heat and Fluid Flow, 24, 470-479, 2003.

4. Benhamadouche S, Laurence D, Jarrin N, Afgan I, Moulinec C. Large Eddy Simulation of flow across in-line tube bundles. NURETH-11 paper 405, Avignon, France, Oct. 2005.

5. Martinez P., D. Alvarez D, Société Française d'Energie Nucléaire - SFEN ST6 meeting "CFD pour la conception et la sûreté des réacteurs", Chatou 29/04/ 2009.

6. Wizman, V., Laurence, D., Kanniche, M., Durbin, P., Demuren, A. Modeling near wall effects in SMC by elliptic relaxation. I. J. Heat & Fluid Flow, 17, pp. 255-266, 1996.

7. H. Ogawa, M. Igarashi, N. Kimura, H. Kamide Experimental study on fluid mixing phenomena in T-pipe junction with upstream elbow. NURETH 11– paper 448, 2005.

8. Pasutto T., Peniguel C., Stefan, Effects of the upstream elbows for thermal fatigues in PWR T Junctions using LES. ICONE-15, Nagoya, Japan, Paper 10410, 2007.

9. Meyers J., B. Geurts B., P. Sagaut P., Edts. Quality and Reliability of LES, ERCOFTAC Series vol. 12, Springer, 2008.

10. Jarrin N., Prosser R., Uribe J.C., S. Benhamadouche S., Laurence D. Reconstruction of turbulent fluctuations for hybrid RANS/LES simulations using a Synthetic-Eddy Method. I. J. Heat and Fluid Flow http://dx.doi.org/10.1016/j.ijheatfluidflow.2009.02.016 , 2009.

11. Uribe J.C., Jarrin N., Prosser R. and Laurence D., Two Velocities hybrid RANS-LES of a trailing edge flow, IUTAM Symposium "Unsteady Separated Flows and their Control" - Corfu Greece June 2007, To appear in J. Flow Turbulence and Combustion 2009.

12. Péniguel C., Rupp I., Juhel JP., Rolfo M., Guillaud M., Gervais N. 3D Conjugated Heat Transfer Analysis in Sodium Fast-Reactor Wire-Wrapped Fuel-Assembly, I.C. on Advances in nuclear Power Plants, ICAPP ‘09 Tokyo, Japan, Paper 9311, 2009.

http://dx.doi.org/10.1016/j.ijheatfluidflow.2009.02.016

1 - UoM-EDF Wiki Collaborative Website : sample test cases.

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