NIMROD TEAM MEETING Austin, TX 3-5 March 1999 Attendees: Tarditi, Bolton, Sovinec, Kruger, Schnack, Nebel, Aydemir, Glasser, Gianakon, Parker, ?? Wednesday, March 3 Dalton reported on the PPPL MHD meeting 8:30 AM STATUS OF THE NIMROD PHYSICS KERNEL (Delayed until 10am due to discussion of MHD meeting.) I. Vacuum region and moving separatrix - Carl Carl had tried linear test external mode test case due to Shafranov. Our original idea had V=0 in the vacuum, which was like having a conducting wall on the plasam, which makes everything stable. Got the best result by having no viscosity or vacuum drag but huge resistivity (DVAC=10**5) in the vacuum. gamma*taua(analytic)=0.03, gamma*taua(nimrod)=0.024. II. Resistive Wall - Scott Scott has not gotten to this. One way to do it is just put drag (makes V=0 at the interface) and have smaller resistivity than in the vacuum, and just solve the usual equations there. In his sense, the "resistive wall" is in the code. Scott will spend ~20% of his time on coupling Morrel Chance's vacuum code to NIMROD for the resistive wall in the thin shell approximation. III. Neo-classical Model - Tom Tom presented the analytic "Hole closure". He has gotten some good results. It has only a saturtion mechanism, not a "turn on" mechanism, but that could be easily done. Anisotropic pressure diffusivity has been implemented, but not yet checked out. IV. GEOMETRY A. R=0 Implementated since APS. Should work on both Tblocks and Rblocks, but Tblocks haven't been tested by Carl. B. Gridding outside separatrix. Interaction between triangle and nimset may have problems. Alfonso, Tom and Carl will look at it. Dalton and Alfonso must checkm with LLNL to understand the definition of the SSPX equilibrium in the eqdisk file. 2. NIMROD PERFORMANCE I. Progress in linear solvers - Alan Coarse grids may of may no solve some of our problems. Iteration counts are large because problem is ill conditioned at large time step. Can't expect more than a factor of 3 imporvement. # of iterations may saturate so that for large dt we may actually be able to get some benefit from taking the large dt. Maybe high S problems will benefit from this. II. Scalar Optimization All told we have gotten about a 40% improvement in performance. Don't expect much more here. III. AZTEC interface (Steve was sick. This was reported by Carl.) Steve is still looking for somebody at SNL to operationally couple AZTEC with NIMROD. 3. APPLICATIONS I. 2-fluid results - Rick Interesting 2-fluid results for RFP show nonlinear generation of n=0 shear flows from the Hall term. There is a nonlinear CFL condition for these 2-fluid calculations. This was not well understood. II. Neo-classical Results already given, III. Spheromak General can calculations: Carl showed very interesting spheromak formation and sustainment results. He'll amplify at Sherwood. SSPX: Need to clarify the input problems with the eqdisk file. IV. NSTX/Columbia: Jon Menard of PPPL to work on applying NIMROD to NSTX. Rick will follow up with Mike Mauel on the Columbia work. V. Others: Electric tokamak - Still working. DIII-D shot 87009 - Sequence of equilibria vs. beta-N have been constructed to get find the marginal point from NIMROD. Then we'll "drive through" the marginal point. FRC/Moqui - Interface is coming out "nicely". RFP?? - Carl has done fairly complete toroidal/circular cross section study. Stay tuned. Kink-ballooning - Tom has contacted Lutjens for the kink/ballooning problem. He has gotten the input data. We'll now be able to do the famous kink-ballooning problem. *****END OF WEDNESDAY***** ********THURSDAY, MARCH 4*********** ENERGETIC PARTICLE MODEL Yang Chen from U. Colorado gave talk on background and capabilities. Goal is to include energetic particle effects in NIMROD. Yang gave an excellent talk that led to much interest and lively discussion. The proposed effort will address energetic minority particles only, not bulk transport like ion viscosity of electron heat conduction. GRAPHICS I. XDRAW - Nina's contract is assured. Curt has 11K, thinks he can get extra 9K for total of 20K. Alan will notify Nina. Alan will forward concerns about MOTIF (not available under Linux) to Nina. II. Poincaré Plots: Will be in next release. III. Other interfaces Everyone must deal with their own interfaces if they use something other than XDRAW. Tom and/or Scott will build an interface to Tekplot. We wolud like users who make interfaces to other packages to give them back to the team for possible inclusion in future pckages. PUBLIC RELEASE I. Web pages Scott has updated the public web pages to include a download form. Scott will check with Walter to make sure the download form has the proper caveats. We've gotten www.nimrodteam.org as a web address. Version 2.2 is the public version. DEVELOPMENT ISSUES: Vacuum region - Carl to continue to refine the present algorithm. Resistive wall - Carl will explore the "Ahmet" model more. Scott will spend 20% of his time on the Greens function model (the VACUUM code??). High S - Tom has implemented a good grid packing. He will make this available to the team. Dalton and Scott will try to push to high S. They will use the FAR case, or something similar. Will try both toroidal and cylindrical geometry. Try cylindrical geometry first. Neo-classical effects - Tom is continuing to improve the closure. Also working on the anisotropic resistivity problem. Everything else is going just peachy!! NIMROD++ : Alan sees no compelling reason for going in this direction. There are many opinions. Ahmet is very interested in this problem (OO approach). Ahmet will think about how to structure a NIMROD-like physics model with OO concepts. T3E allocation Keep on using it!!!!!! TEAM FUNCTION Alan: We need more conference calls, maybe once a month. Discussion about $$. All will be well, as long as we do the right thing. ************END THURSDAY MARCH 4************* ***********FRIDAY, MARCH 5**************** Extended discussion with Scott Parker re: 1. Energetic particles in NIMROD (minority species) Scott will submit proposal to DOE ASAP. Will send draft to Dalton. 2. Kinetic ions (majority species) Same algorithm as in 1, above, but no longer minority. In principle, could make all ions kinetic. 3. Kinetic electrons More difficult problem. We will try to have team teleconferences on a monthly basis. Curt will set date for the next conference and will arrange the conference call. We will NOT meet at Sherwood in Atlanta (at least formally). Next team meeting: Dalton will check out the possibility of Incline Village, Tahoe. Otherwise, LANL will host.