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Limitations

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Michael Hirsch, Ph.D edited this page Jan 4, 2019 · 1 revision

Any model has limitations, here are some of GEMINI's limitations:

  1. Generating equilibrium conditions can be a bit tricky with curvilinear grids. A low-res run can be done, but it will not necessary interpolate properly onto a finer grid due to some issue with the way the grids are made with ghost cells etc. A workaround is to use a slightly narrower (x2) grid in the high-res run (quarter of a degree seems to work most of the time).
  2. Magnetic field calculations on an open 2D grid do not appear completely consistent with MATLAB model prototype results; although there are quite close. This may have been related to sign errors in the FAC calculations - these tests should be retried at some point.
  3. Occasionally MUMPS will throw an error because it underestimated the amount of memory needed for a solve. If this happens a workaround is to uncomment (or add) this line of code to the potential solver being used for your simulations:
mumps_par%ICNTL(14)=50

If the problem persists try changing the number to 100. 4. There are potentially some issues with the way the stability condition is evaluated, i.e. it is computed before the perp. drifts are solved so it is possible when using input data to overrun this especially if your target CFL number is > 0.8 or so. Some code has been added as of 8/20/2018 to throttle how much dt is allowed to change between time steps and this seems to completely fix this issue, but theoretically it could still happen; however this is probably very unlikely. 5. Occasionally one will see edge artifacts in either the field -aligned currents or other parameters for non-periodic in x3 solves. This may be related to the divergence calculations needed for the parallel current (under EFL formulation) and for compression calculations in the multifluid module, but this needs to be investigated further... This do not appear to affect solutions in the interior of the grid domain and can probably be safely ignored if your region of interest is sufficiently far from the boundary (which is alway good practice anyway).

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