Code-Code comparisons

19/11/2004 1 ITPA-2004-11 Coster Code-Code

Code-Code comparisons

D. P. Coster*, X. Bonnin**

*Max Planck Institute for Plasma Physics,

EURATOM Association, Garching, Germany

** Max Planck Institute for Plasma Physics,

EURATOM Association, Greifswald, Germany;

CEA-France; Paris-XIII

Goal

• Three major edge codes in wide-spread use, and in use for JET discharges • Two of these with developer knowledge at JET

• To compare the edge codes for a series of cases with increasing physics complexity, to understand the origin of the differences that arise, and to “validate” the codes

• Started with EDGE2D-NIMBUS, SOLPS (B2-EIRENE) and UEDGE

• Lack of UEDGE expertise at JET caused UEDGE to drop out (welcome to join back, do need developer level expertise to be available, though)

• Progression

– D, no drifts [completed]

– D, drifts [started]

– D+C, no drifts [next] – D+C, drifts [last]

SOLPS/EDGE2D-NIMBUS comparison, first results

– Pure D

– Same transport coefficients – Same boundary conditions

– Same feedback gas puff to control separatrix density

– Strong differences

• 3 cases

– EDGE2D-NIMBUS – SOLPS, fluid neutrals – SOLPS, kinetic neutrals

• Suggested we had a lot of work ahead

Some observations

• Comparisons facilitated by

– Being able to operate the codes on the same grid

– Being to plot the results from both codes on the same graph, easily

• Did this by porting the JET “TRAN” file facility to SOLPS

– Not necessarily the best long term solution – But could be done quickly

– Having Developer-level expertise for both codes available at the same site for extended periods of time

SOLPS/EDGE2D-NIMBUS comparison, flux limiters

different assumptions about kinetic parallel electron and ion energy flux limiters

• SOLPS had been using flux limiters for both electrons and ions

• EDGE2D-NIMBUS had the electron flux limiters coded, but not used in these runs

• Having the same flux limiter choice in both codes brought the two closer together

SOLPS/EDGE2D-NIMBUS comparison, additional differences

• Also “explained” a feature that had been seen on the poloidal ion temperature profile --- eliminated when ion thermal flux limiter switched off

• Feature also decreased when the gas puff was switched from localised (SOLPS) to distributed (EDGE2D-NIMBUS)

• An additional difference in the starting cases was traced to M=1 vs M>=1 at target

SOLPS/EDGE2D-NIMBUS comparison, final 5e18

comparison

– 5e18 upstream density – Agreement is very good!

• Though differences remain

• Not thought worth spending too much more effort chasing the remaining differences

• Particularly as

– Some of the difference thought to come from neutrals

SOLPS/EDGE2D-NIMBUS comparison, final 1e19

comparison

– 1e19 upstream density

– Slightly worse comparison than the lower density case

• Suspect this is due to different neutral treatment

– See next slide

SOLPS/EDGE2D-NIMBUS comparison, final 1.5e19

comparison

– 1.5e19 upstream density

– Starting to see differences that come (probably) from differences in the neutrals code (NIMBUS vs

EIRENE)

• Is an effort to produce EDGE2D-NIMBUS

– To see some of the effects, SOLPS cases were done dropping the energy per ionisation

SOLPS/EDGE2D-NIMBUS comparison, drifts 5e18

– 5e18 case

SOLPS/EDGE2D-NIMBUS comparison, drifts 1e19

– 1e19 case

SOLPS/EDGE2D-NIMBUS comparison,

drifts/poloidal velocities

• Poloidal profiles of the velocity for 5e18 and 1e19 cases • Work has been on hold for some months

– JET not in operation, therefore no secondments – Xavier shifting jobs, David busy with other things

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MDSPLUS used to store SOLPS runs

SOLPS

[JET, IPP,…]

Analysis program (jetdsp, cview, radisplay,

idl, matlab) [Fusion Lab] solps-mdsplus. aug.ipp.mpg.de (MDSPLUS server) [Garching] •Linux server •1GB RAM •2 cpus

•Using MR-AFS to provide storage •11062 shots

•307 GB data •In the Garching DMZ

•Any of the standard MDSPLUS experimental plotting programs can be used

•Data can be also be accessed via IDL, MATLAB •New postprocessing routine “b2md”

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Code and Experiment can be plotted with the same tool

1.00 1.10 1.20 1.30 s coord (m) 0 2•1019 4•1019 6•1019 8•1019 1•1020 AUG data AB:10817/+solps/diag/\top.AUG.DIA:[email protected]

AE:*/*/*/AA_raw & time=AA_time_raw & [email protected] AG:*/*/*/AC_raw & time=AA_time_raw & [email protected]

cview-prof (gdc) v2.41 - User: dpc - Mon Oct 25 11:25:38 2004