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Code_Saturne®: EDF’s general purpose CFD software goes Open Source

Code_Saturne: EDF’s general purpose CFD software goes open source http://rd.edf.com/code_saturneRencontres Mondiales du Logiciel Libre, Amiens, 11/07/2007 [email protected]

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Why CFD (Computational Fluid Dynamics) at EDF?

Production• Improve competitivity, reliability and safety of EDF power plants (nuclear or not)• Maintenance optimisation, lifetime management• Response to specific situations (flood, heat wave, incidents)

Preparation of the future• New technologies for power generation• Innovative and renewable energies• Influence of climate changes

Promotion of sustainable development• Help customers improve their energy consumption

Global challenges• Evaluation of environmental impact, waste management• Development of future simulation tools


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1General elements on Code_Saturne


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Technology • Co-located finite volume, arbitrary unstructured meshes, predictor-corrector method• 500 000 lines of code, 49% FORTRAN, 41% C, 10% Python

Development • 1998: Prototype (long time EDF in-house experience, ESTET-ASTRID, N3S, ...)• 2000: version 1.0 (basic modelling, wide range of meshes)• 2001: Qualification for single phase nuclear thermal-hydraulic applications• 2004: Version 1.1 (complex physics, LES, parallel computing)• 2006: Version 1.2 (state of the art turbulence models, gui)• 2008: Scheduled release of version 1.3 (massively parallel, ALE, code coupling, ...)

Released as open source (GPL licence) Beta versions (1.3.f and following) pre-released

Broad validation range for each version• ~ 30 cases, 1 to 15 simulations per case• Academic to industrial cases (4 to 2 000 000 cells, 0,04 s to 12 days CPU time) • Linux (workstations, clusters), Solaris, Irix64, Fujitsu VPP, Tru64 (AlphaServer),

Blue Gene/L, PowerPC 4 and 5

Qualification for single phase nuclear applications• Best practice guidelines in specific and critical domain• Usual real life industrial studies (500 000 to 3 000 000 cells)

Code_Saturne: general features


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Code_Saturne: main capabilities

Physical modelling• Laminar and turbulent flows: k-ε, k-ω

SST, v2f, RSM, LES• Radiative heat transfer (DOM, P-1)• Combustion coal, fuel, gas (EBU, pdf, LWP)• Electric arc and Joule effect• Lagrangian module for dispersed particle tracking• Compressible flow• ALE method for deformable meshes• Conjugate heat transfer (Syrthes & 1D)• Specific engineering modules for nuclear waste surface storage and cooling towers• Derived version for atmospheric flows (Mercure_Saturne)• Derived version for eulerian multiphase flows

Flexibility• Portability (UNIX and Linux)• GUI (Python TkTix, Xml format)• Parallel on distributed memory machines • Periodic boundaries (parallel, arbitrary interfaces)• Wide range of unstructured meshes with arbitrary interfaces• Code coupling capabilities (Code_Saturne/Code_Saturne, Code_Saturne/Code_Aster, ...)


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Basic software architecture characteristics of Code_Saturne


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FVMlibrary

Code_Saturne

elements

Code_Saturne

Pre-processor (Envelope)

mesh import mesh pasting

domain decomposition

Post-processing

output

Restart files

Meshes

Parallel Kernel

ghost cells creationperiodicity

CFD Solver

code coupling

parallel treatmentCode_Saturne

SyrthesCode_Aster

Salome platform...

GUI

Xml data file

External libraries (EDF, LGPL):• BFT: Base Functions and Types• FVM: Finite Volume Mesh

BFT library

I/Omemory management

parallel meshmanagement


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Classical domain splitting for parallelism (using MPI)

General Finite Volume discretisation

• Equations written as fluxes through faces sparse matrix• For the equation on cell i, the only necessary values are those of cell i and its

neighbours (cells sharing a face with cell i) synchronised ghost cells• Some algorithms require an extended neighbourhood (cells sharing a vertex)• Implemented using MPI_Isend, MPI_Irecv, MPI_Waitall and MPI_Allreduce

PWR lower plenum decomposition (Metis)

Proc. 1 Proc. 2

Proc. 1 Proc. 2


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Parallelism/periodicity

Translation: same treatment as for parallelism

Rotation is treated similarly, but implementation is more complex

• Vectors and tensors require rotation (component coupling) explicit

Parallelism and periodicity can be combined

Domaine de calcul distribué sur 4 processeurs

Champ de vitesse sur le domaine complet

With periodic boundaries

Parallel treatment Periodic treatment

PeriodicityDomain partitioning

Initial meshMesh

Data exchangeData exchange

Ghost cells


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Environment and documentation

Environment• Pre-requisite: compilers

•

C (cc, gcc, xlc, icc, ...)•

FORTRAN (f77, g77, gfortran, frt, f90, xlf, ifort, ...) • Pre-requisite for parallel computing:

•

MPI: lam, openmpi, MPICH2•

Metis or Scotch for better load balancing (optional; linked with the Preprocessor)

• Pre-requisite for Graphical User Interface:•

Python•

Tcl/Tk, Tix•

Xml2• Optional data exchange libraries:

•

MED, HDF5•

CGNS• Misc.:

•

Zlib

Documentation• Quality Assurance, GUI• Online user and programmer’s guides• Support hot-line : [email protected]

(no waranty)• Internet home page under construction :

http://rd.edf.com/code_saturne


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3General capabilities of Code_Saturne


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Supported meshes

Mesh generators• Simail: easy-to-use, with command file, but no CAD• I-DEAS Master Series: powerful, CAD, no Linux version• ICEM-CFD, GAMBIT• IGG-HEXA (NUMECA), Comet-Design (STAR-CCM), • Harpoon, GMSH…

Formats• Above mentioned mesh generators + MED, CGNS, EnSight Gold…

Cells: arbitrary arrangement of polyhedra of any type• For example: tetrahedra, hexahedra, prisms, pyramids, n-faced polyhedra, ...

Arbitrary interfaces: « any type of mesh / format » + « any type of mesh / format »• Meshes may be contained in one single file or in several separate files• Order of meshes has no influence• Arbitrary interfaces can be selected by mesh references• Expertise may be required if arbitrary interfaces are used:

•

in critical regions •

with LES•

with very different mesh refinements •

on curved CAD surfaces


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Mesh examples

Example of mesh with stretched cells and hanging nodes

Example of composite mesh

3D polyedral cells

PWR lower plenum


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Advanced post-processing capabilities (FVM library)

FVM library capabilities

• fully parallel treatment• post-processing files written while calculation is running• optional discard of non-standard polygons or polyhedra• optional tessellation of non-standard polygons or polyhedra adaptation to format

or post-processing tool featuresUser-defined, time dependent, post-processing meshes and variables

Helium injectiontrail C>0.05

Stratified T junctionVelocity field at the boundary of the zone where T<T0


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Arbitrary Lagrangian Eulerian method (ALE)

Deformable meshes

• mesh deformation estimated from boundary conditions• possibility for the user to specify the movement of any node• internal coupling with user-defined moving structures (frictional spring law)• external coupling with the structure mechanics tool Code_Aster

Channel flow with two moving cylinders defined as independent structure with internal coupling

(mesh viscosity = 1 (blue) or 1010 (red))


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Double cylinder flow with ALE internal coupling


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Large Eddy Simulation (unsteady turbulence modelling)

Dynamic model (with filter requiring no homogeneous direction)

Wall treatment: refinement with hanging nodes or wall functions

Synthetic turbulence (for inlet and coupling with RANS)

Application example: thermal fatigueContrary to classical RANS approaches,Large Eddy Simulationallows to represent the large structures of the flow, and, by thermal coupling with the structure, to determine the wall thermal loading.

Wall temperature (Syrthes)

Fluid temperature Code_Saturne

Time

Wall refinement with hanging nodes

Synthetic turbulence method at inlet


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Specific physics capabilities

Lagrangian method • Stochastic modelling with 2-way coupling (momentum, heat, mass)⇒ transport & deposit of droplets, ashes, coal, corrosion products, radioactive particles, chemical forces, ...

Gas combustion• EBU, pdf modelling (LWP: mean, variance and covariance of mixing rate & fuel mass fraction)⇒ combustion turbines (optimisation, pollutants…)

Coal combustion• Homogeneous Eulerian approach (granulometric classes, Kobayashi for devolatilisation)⇒ pulverized coal furnaces (optimisation, slagging, pollutants)

Semi-transparent radiative heat transfer • Discrete Ordinate Method and P-1 (L0,qi) model for optically thick media⇒ coal furnaces, electric arc

Joule effect and electric arc• Electromagnetism and coupling (momentum and heat transfer)⇒ glass furnace, plasma, electric transformers

Compressible flow• Density, momentum, total energy ⇒ electric transformers, turbines

Syrthes coupling for conjugate heat transfer and transparent radiative heat transfer• Independent FE solver with tetrahedral mesh and arbitrary fluid-solid interface⇒ thermal shock, striping, fatigue…

Fuel combustion, ionic mobility under development


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Lagrangian modelling for multi-phase flows

Generally used to obtain refined statistics on a dispersed phaseStochastic modelling with 2-way coupling (momentum, heat, mass)Some applications:

• particle trajectories in cyclone separators• resident times and combustion in polydispersed pulverised coal furnaces • impact phenomena (turbine blades)• deposit, slagging and fouling (PWR heat exchangers, coal furnaces…)


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Porcheville French plant Separator efficiency

Air

0

1

2

3

4

5

6

0.1 1 10 100 1000

µm

% v

ol.

Gas inlet

Gas outlet

Secondary cells

Primary cells

Unburned fuelD = 2mm

Ashes D50 = 40µm

1016 mm

Gas inlet

300 mm

Primary cell


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Pollutant

prediction

(Nox)

CFD complements or replaces data that turn out to be difficult to obtain

constructor data

measurements

Pollutant prediction in Gas Turbine Rio-Bravo 495 MW Turbine

3D computation Film cooling, swirled inlet EBU combustion model

Refined chemical analysisIn zones defined from T and f


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Pulverised coal combustion

Nox, slagging and fouling, flame stability, temperature peaks3D modelling + refined chemical analysis

⇒ optimization of maintenance and performance

Primary air Secondary air

Ashes

Water

Limestone

Coal

Cyclone

Towards recuperator and smoke treatment

Simplified and partial sketch of a pulverized coal combustion boiler


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Glass furnace

Joule effectUse of constant complex potential to account for tri-phase alternating currentOffset effect accounted for

Strongly variable physical properties, especially viscosity Specific pressure-velocity coupling to support large time steps

temperature

Joule W/m3 (vert., log.)

Re(Pot) V (horiz.)


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Electric arcs applications

Applications• Temperature peak in electric transformers• Combustion/Vitrification of radioactive waste (medium activity, long life)• Arc default effect in closed posts

Phenomena• Joule effect and Laplace forces• Radiative heat transfer

Difficulties• Strong source terms: 28 MJ on tube 1,7 m long and 10 cm diameter• Unsteady phenomena: 2 arcs 20kA, 1300 V during 500 ms• Variable physical properties: temperature from 300 to 30000 K

Oil

Paper &

Copper

ExperimentSimulation Effect of arc default


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Thermal fluide-structure interaction Conjugate heat transfer, radiative transfer

Coupling with thermal code Syrthes

Storage

• design expertise

Valve numerical qualification

• thermal shock experiments

PWR vessel life time (LOCA)

• refined and local thermal- hydraulic coupled approach


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Matisse engineering module

Numerical tool for the design of nuclear waste storage facilities

• Integrated Code_Saturne

module aimed at engineering needs

• No user subroutine needed• Parametric mesh creation controlled by

GUI (generic shape) with Simail tool• Homogeneous approach for the

calculation of the flow

temperature field


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Cooling towers engineering module

Plumes• natural convection

Fans and packing • turbulence, head losses, forced convection

Rain-zones and frost • 2-phase flows with heat and mass transfer


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Mercure_Saturne

for atmospheric flows

Specific models • boundary conditions• atmospheric boundary layer• hydrostatic pressure• radiative source terms• micro-physics and chemistry of

pollutants

External derived version• based on Code_Saturne• currently being transfered in the

standard version of Code_Saturne


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Coupling of Code_Saturne

with itself (under development)

Objective: coupling of several overlapping computational domains• RANS/LES coupling for turbulence averaged RANS method in most part

of the domain and unsteady LES zoom in specific areas• Fluid/structure interaction with large displacement (unreachable to ALE)

Two kinds of communications needed• Data exchange at the boundaries• Volumic forcing on the intersecting domains

Main issues to be tackled• Optimised fully parallel localisation

already efficient but improvement still possible• Conservativity at the interfaces• Physical coupling when different physical

models in each domain


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Chimera method: FSI for tube bundle configuration


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RANS/LES coupling

normal coupling tangential coupling

LES region


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4Parallel performance of Code_Saturne


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High Performance Computing with Code_Saturne

For research and production (in addition to local resources: small clusters):

EDF’s Blue Gene (8000 procs) CCRT (Computing Centre for Research and Technology)

For benchmark :

IBM Power PC 5 Cluster / Myrinet

IBM Computing On Demand

Mare Nostrum

B.S.C.


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Parallel Performance - FATHER test case

“FATHER” LES case (thermal fatigue in a T-junction)• 1M cells• In 2003, a full run required 63 days using one vector processor on EDF's Fujitsu VPP 5000

computer for ten physical seconds simulated (50 000 iterations).

• In 2004, the same run required 10 days on 32 processors of an HP AlphaServer (CCRT)

• Now on Blue Gene EDF Machine: will require less than 1 day on 512 processors


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“HYPI” LES case (isothermal T-junction)• 10 Million cells• The full run required 22 days using

400 processors on an IBM Power PC 5 cluster (DCCoD)

Parallel Performance – HyPi test case


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Current frontier with Code_Saturne

Calculation under way with 100 million cells• PWR assembly mixing grid• calculation on 4 000 to 8 000 procs• major lock due to mesh generation

fuel rods


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Current frontier with Code_Saturne


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Validation and qualification of Code_Saturne


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Validation Academic and industrial test-cases

N°

Cas

e

Dim

ensi

on

Ste

ady/

Uns

tead

y

Lam

inar

/Tu

rbul

ent

1 Wake of a circular cylinder 2 U L2 Lid driven cavity 2 S L3 Channel flow Re*=1655 1 & 3 S T4 Dune 2 S T5 Asymmetric diffuser 2 S T6 Tube bundle (Fedora) 2 S T7 Head losses 2 S T8 180° circular tube bend 3 S T9 Simplified car body 3 S T10 Homogeneous Isotropic Turbulence 3 U T11 Mixed convection 2 S T12 Betts' cavity (natural convection) 2 S T13 Impinging jet 2axi S T14 Jet in pool with thermal fluctuations 2axi S T15 Stratified flow in pipe (Supernimbus) 3 S T16 Multi species mixing in pipe (Echo) 3 S T17 Thermal mixing zone (Rra) 3 S T18 Thermal shock (Creare) 3 U T19 Premixed flame (Oracles) 2 S T20 Diffusion flame 2axi S T21 Coal combustion (Cerchar) 3 S T22 2-phase flow jet (lagrangian) 2axi S T23 Shock tube 1 U L24 Axisymmetric arc (Pfender) 2axi & 3S T25 Radiative heat transfer (Selçuk) 3 S26 Syrthes coupling 2 S T27 Foo 3 S T28 MED format 329 2-phase flow, lagragian (Hishida) 2a et 3 S T30 Reverse hot jet (mixed convection) 2 S T31 Oscillating channel 2 U T


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Qualification for nuclear thermal-hydraulics

Quality and trust important for nuclear safety

• Complements standard validation for a specific domain of application•

comparing to reliable data •

determining the limitations of the results •

edicting best practice guidelines

temperature


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Users and partners around Code_Saturne


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Current users and partners

Outside EDF [France, UK, Poland, China, Algeria]• CEA le Ripault (arc and plasma)• CEA Saclay, CEA Grenoble• CEREA (atmospheric)• CETIM (algorithm)• CS-SI (code coupling)• ENSTA, ENPC(teaching)• ENSIL (arc and plasma)• IMF Toulouse (multiphase, FSI)• LCD Poitiers (combustion)• LEA, LET Poitiers (turbulence)

• Cooling towers• Heat pumps• Aeraulics (health and safety, environment…)• Atmospheric environment • Salome project• Electric arc, plasma, ionic transport• Glass furnace

• LMM Paris 6 (LES, atmospheric)• ONERA (electric arcs)• TPRI China (combustion)• TREFLE, U. Bordeaux (algorithm)• U. Manchester UK (turbulence)• UST Lille (FSI)• UST Oran Algeria (turbulence, LES, FSI)• UT Gliwice Poland (combustion)• Valeo (acoustic)

EDF R&D (70 users)• Nuclear thermal-hydraulic applications• Combustion (coal furnaces, gaz turbines…)• Thermal loading• Fluid-structure interaction• Valves• Acoustic

EDF DIN SEPTEN• EDF Basic Design Department: fossil-fired furnaces and nuclear plants


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Why go open source?

Ease up the collaboration process• No contract, collaboration agreement, nor non-disclosure-agreement to sign

before giving the sources• Simplicity for any potential partner to test Code_Saturne

Enlarge the user community and the range of applications• Better national and international recognition of Code_Saturne• Larger feedback and better validation of Code_Saturne• Provide industry with a open software

Enlarge the developer community• Capitalise in Code_Saturne

the work and knowledge of partners

• External involvement in the Code_Saturne

support• External developers to support the EDF development team• External developers to provide their own developments on their own

applicationsCoherent with EDF’s open source strategy

•

Code_Aster, Salome platform, OpenTurns, ...


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Code_Saturne

open source practical info

Distribution of Code_Saturne• GPL licence, auxiliary libraries (BFT and FVM) under LGPL licence• Download page http://rd.edf.com/code_saturne (temporary page but permanent address)

• Downloadable versions:•

1.3.f beta version currently available•

1.3.0 frozen non fully validated version in august 2007•

1.3.2 fully validated version in january 2008Contact and support around Code_Saturne

• Contact and support address [email protected] (no warranty on availability of support)

• User’s Club meeting November 26-27 2007 in Chatou (78)• To appear in the mailing list [email protected]• Initial training sessions in march and november (but not for free!)

External development integration• Any useful external contribution welcome• For easier licence management, any contribution given for integration will be under

EDF’s copyright• Contributors will be clearly mentioned in the author’s list•

Code_Saturne

is a trademark property of EDF

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