Runtime AMR (M5)

Milestone M5 (#74) regrids during the time loop. [amr] frequency = 0, the value of every input so far, keeps the AMR of the initial condition only; n > 0 regrids every n steps. The library already holds a complete regrid step (adam_object%amr_update: the tree adapts with 2:1 balance, the interior data is prolonged or restricted, the blocks are redistributed, the maps rebuilt).

Phase	Content
P0	tests the library regrid step on its own and puts the hooks in place
P1	the conservative prolongation FLUME regrids with ([amr] regrid_prolongation, default conservative)
P2	regrids FLUME on the CPU: the markers combined, the Löhner estimator, the solids' distance function and the flux register rebuilt, restarts across regrids (numerics)
P3	regrids the FNL backend by a host round trip
P4	the accuracy of runtime AMR (AV)

The input keys are described in setting up runtime AMR.

Case	ID	What it verifies
Regrid round trip and input contract	RG (rg0 to rg2)	the library regrid in isolation: bookkeeping over 1, 2, 3 ranks, the conservative prolongation exact on the integral and in range, the frequency and regrid_prolongation contracts
Runtime regrids in FLUME	RG (rg3 to rg6)	conservation through regrids, bitwise restart across regrids, the immersed solid, CPU against FNL
Accuracy of runtime AMR	AV (av2 to av8)	tracked runs against uniform-fine runs on the vortex, Sod, the MHD blast, the field loop and the cylinder; rank and backend invariance
MHD blast symmetry on the flux-splitting path	#77, av3c	why the low-β blast loses its point symmetry on weno flux splitting, and the Riemann-flux path that keeps it

Run every leg:

cd src/tests/flume/verification/regrid
./check.sh && ./accuracy.sh                                                           # CPU
FLUME_EXE=$PWD/../../../../../exe/adam_flume_fnl ./check.sh --legs rg3,rg4,rg5
FLUME_EXE=$PWD/../../../../../exe/adam_flume_fnl ./accuracy.sh                        # FNL
./check.sh --legs rg6 && ./accuracy.sh --legs av8                                     # CPU against FNL

The figure (regrid.png) is drawn by make_doc_figures.py from the CPU work directories av2-tracked and av4-glm-tracked that regrid/accuracy.sh leaves (no make_doc_runs.sh group):

exe/.regression-venv/bin/python src/tests/flume/verification/make_doc_figures.py --out docs/public/flume --only regrid