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# This readme presents results of a convergence scan
# with the input file in sim/inputs on Summit.
#####################################################

A convergence study, starting from an input file similar to ./sim/inputs (with
a different set of physical parameters generated the APOSMM generator in a
LibEnsemble run) is presented below. The only parameter changed to go from one
resolution to the next is amr.n_cell.

resolution   amr.n_cell   duration    f
res0          16  1024      10s       2.6340181298685122e-05
res1          32  2948      20s       5.074892524831451e-07 <- the one we've been running so far
res2          64  4096      54s       4.557730935993e-06
res3         128  8192     214s       5.683672880520962e-06
res4         256 16384    1092s       5.667607648747023e-06

I ran the last run on 2 GPUs instead of 1, and it took 780s instead of 1092s,
meaning we can run it on either 1 GPU or 2. That way, we can explore it either
having all resolutions on the same number of GPUs, or on different number of
GPUs. In the end, we would probably be interested in the former, which can also
be further investigating my going to higher resolution.

The simulations can be run with the same input file, with the following changes:
- The timeout in the batch script should be larger for higher resolutions (see
  numbers above)
- The jsrun command should be modified as, e.g., "jsrun ... warpx.exe inputs
  amr.n_cell=128 8192" for resolution res3

Note that this test shows a nice converge for a case with relatively high emittance.
In the optimization process, some runs will have a lower emittance (potentially
10x), and they may require a higher resolution to reach the same level of
convergence. Let us keep this in mind, and maybe add a res5 to the list above.
This high-resolution one should also fit on 1 GPU, but it will be worth
testing.
