NIMROD TEAM MEETING
2628
January 2000
Santa
Fe, New Mexico
MINUTES
WEDNESDAY,
JANUARY 26
9:30 AM12:30 PM
I .Discussion of
ongoing applications

Neoclassical Tearing Mode (Tom)
4
closures are in the code. There is HirschmanSigmar and 2
approximations to that closure plua rhw hole model.
APS
results were not an NTM but a tearing mode. Looking for an NTM in a
new test case. So far have found only numerical instability. This is
being analyzed (new normal modes??).

Stochastic transport (Eric, Carl)
Look
for stochastic transport in RFPs. Use Eric's kinetic closure to
estimate radial thermal diffusivity.
Eric
will put a parallel version of the field line tracing code on the T3E
so that everyone can use it,

Spheromak modeling (Carl, Alfonso)
A
paper is being prepared on Carl's spheromak results. Flux
amplification vs, applied voltage for many different parameters.
Calculations
of SSPX indicate that the triangles are working well. No problems are
seen at the boundary between the quads and the triangles. The problem
is that the equilibrium from Corsica does not satisfy regularity. Don
Pearlstein is working on that problem.

FRC (Alfonso)
Smooth
FRC equilibria have been obtained by filtering the initial data. The
beginnings of the tilt mode have been seen. One question is why
interpolation seems to introcude noise.
 D3D Highbeta disruption (Alfonso)
There
are discrepencies in gamma vs. betaN for NIMROD and GATO. This needs
to be understoon. NIMROD finds a resistive mode below the ideal MHD
marginal point.

HighS (Dalton)
Linear
cylindrical cases have gone to high S (10**9). Still need more
convergence info for the S=10**9 case. Toroidal calculations are
underway.

Twofluid RFP (Rick)
Trying
to isolate the instability that grows out of the origin when 2fluid
efffects are included. Some indications that it may be related to the
electron advection. Could be related to regularity??
Also
attempting to put gyoviscous effects into the model.

??
2:00
PM  6:00 PM
II.
Development

Higher order elements (Carl)
The
previous good convergence results have been confirmed for cases with
a degenerate (r=0) point. Still need to implement this ansatz into
the preconditioners, and for regularity conditions in poloidal
representations. Also need to do it for triangles.
We
may have a released version with biquadratic elements by about April.

Parallel computations (Steve P.)
No
progress; work continues.

Vacuum (Scott K.)
No
progress; work continues. Work on the passive advection of the shape
variable will begin soon.

Resistive wall (Tom)
Tom
has been concentrating on NTMs. We're leaning toward using Morrel
Chance's code for the external vacuum solution.

Neoclassical closures (Tom)
Discussed
above.

Kinetic closures/particles (Charlson)
Trying
to push particles in the NIMROD fields. Code is written but there are
problems with the particle pushing (don't yet get the right orbits).
Aim is to have accurate particle pushing by Sherwood meeting.

Pre/postprocessing issues (Scott K.)
Web
seems to be working well.
Rostom
has to work to get funding to Nina!!!!!
Please
put your results on the web in html format so we can copy the
figures.

Computations on tblocks (Alfonso)
Already
reported.

Flows
Higher
order elements may help here because we have a theoretical basis for
minimizing the div(b) error. Now we can revisit the timestepping
scheme.

??
DINNER
AT THE SHED
THURSDAY, JANUARY 27
9:30
am  10:30 pm
III.
Status of PSACI (Dalton)
Dalton
reported status as he knows it.
10:30 am  12:30 pm
IV.
Develop plans and goals for next 3 months
For
reference, here are the milestones from the November team meeting:
GOAL
RESP. PERSON DATE COMMENTS
1.
Res. wall BC. implemented Tom. G 06/00 Changed from Scott K.
We
will use Morrel Chance's code to get the vacuum response. This seems
to be a reasonable approach. There are 2 issues: 1) coupling the bc.
to the NIMROD solution; 2) the Green's function. Tom will start with
a slab geometry to test issue 1. We'll move on to 2 when 1 is
understood.
This
milestone includes the incorporation of Chance's code into NIMROD .
2.
Lin. highbeta disr. physics Alfonso 04/00 linear by Sherwood
There
are presently results for gamma vs. betaN for both nimrod and GATO.
Nimrod results are about 20% larger This is near the marginal
stability point. We don't understand these differences but they
shouldn't keep us from going ahead with the nonliear calulations.
3.
Linear vac. validated w/GA Scott K. 04/99 Ming to get case to SK for
Sherwood
Need
to get toroidal case for linear validation. Should be complete by
Feb.
4.
Nonlinear vac. implemented Scott K. 04/00
Need
to 1) track the passive scalar shape function with 3d advection; and
2) modify the code to have 3d resistive diffusion. Will do this
semiimplicitly.
5.
Push particles in NIMROD fields Scott P. 04/00 drift orbits
3D
particle push by Sherwood, not parallel (Charlson)
6.
AZTEC into current ver. Steve P. 04/00
Done
in version 2_3_2. Get AZTEC fully integrated into the "quadratic"
version of the code. Steve may lose his funding. It is important that
Steve get more fundng.
7.
OO/C++ structure Ahmet 11/99 ???
Ahmet
hasn't shown up at the last 2 meetings, nor has he participated in
team email discussions. He hasn't delivered on his promise to report
on OO/C++ methods in MHD simulation. It's not clear what his role is,
or where he's spending the NIMROD money that he got this year.
8.
"Fully functional" high ord. eles. Carl S. 04/00
On
track and on schedule. Still needs to be implemented on triangles.
9.
Neoclass. paper submitted Tom G. 12/99
A
NTM has not yet been found. Destabilizing perturbed bootstrap
currents have been sen, but they are not large enough to cause island
growth. There is also a numerical instabiliy related in part to
electron advection that is not well understood. Work is proceeding.
10.
2fluid multihel. RFP Rick N. 04/00 Numerical problems
Still
need to get past numerical instability. Comes from 2fluid R=0. Also
may be related to the electron advection.
11.
Compete SSPX case Alfonso 04/00 Problems w/triangles
Problems
with the triangles appear to have been solved (ie., there was no
problem). Te problem is that the SSPX equilibrium provided by LLNL
does not satisfy the regularity conditions at R = 0. We cannot
proceed further until LLNL solves this problem.
12.
Flow and highS in ET J.N. 04/00 HighS works well, flows don't
Flow
problems still not solved.
13.
Demo. of nonlinear highS Dalton 04/00
S=10**9
case needs to be understood better (better radial and poloidal
resolution). Toroidal case at S=10**5 is underway. Hopefully this
will be more interesting in the nonlinear regime.
14.
Formulate diamag. corrections Chris H./Jim C. 04/00
Chis
should write a brief paper/report on how we might incorporate FLR
effects within the 2fluid model.
15.
General closure implementation Eric. H. 06/00
Eric
will implement a general implementation of closures (heat flux, etc)
into the NIMROD physics kernel.
2:00
pm  4:00 pm
Continue
development of plans/goals
4:00pm
 5:00pm
V.
Discussion of team issues
FRIDAY, JANUARY 28
9:30am
 11:30 am
VI.
Continue discussion of team issues
11:30am
 12:00 noon
VII.
Date and location of next team meeting(s)
VIII.
Adjourn