Functions
	F (a)

	build (grid, bfp)

	vel (s)

	check (label, u, ref, absolute)

	run (grid)

	main ()

	test_balanced_force_restart ()

Variables
	N

	NZ

	G

int	TOL = 1e-12

	RHO = np.where(np.arange(NZ) < NZ // 2, 1000.0, 1.0)[None, None, :] * np.ones((N, N, NZ))

Detailed Description

Gate: the balanced-force projection's pressure split P = P_dyn + P_b never counts the balanced
pressure twice (doc/collocated_varrho_forces.md §4.6.2, the re-split rule).

The option keeps P the total pressure and P_b ("p_balanced") its balanced part; a continuing step
does P += X - P_b, P_b = X. When P_b is NOT the split of the current P -- steps with the option off
moved P, or a restart restored "p" but not "p_balanced" -- that update adds the balanced pressure a
second time (measured before the fix on this column: a restart gave max|u| 1.25e-2 against 7.8e-14
continued; OFF 400 steps then ON gave 1.27e-2). The rule: such a step RE-SPLITS (P_b = X, P
unchanged), and restoring "p_balanced" together with "p" keeps the split.

Configuration: a walled ratio-1000 column (8 x 8 x 24, heavy lower half, walls at -z/+z, mu 0.1,
dt 1, g 0.1, Stokes, Chebyshev rtol 1e-12), on SolverColocated (V8: the option is its default) and
on Solver (option explicitly on). Scenarios, each against its twin:
  continued        30 steps, then one more               (the reference level)
  restart          u, v, w, p restored into a fresh solver, one step (re-split)
  restart + P_b    u, v, w, p and p_balanced restored, one step (keeps the split)
  OFF -> ON        400 steps OFF, then ON for 1 and 6 steps, against the OFF run continued
Gates: every scenario's velocity differs from its twin by < 1e-12 (max over u, v, w), and the two
restarts stay below 1e-12 absolute. On a static force a re-split step IS the OFF step, so the
OFF -> ON run tracks the OFF run to round-off; its absolute level is the OFF transient's (1.8e-4
cell velocity on V8 at step 400, exact on the staggered 1-D column), not the continued ON run's.

Run: OMP_NUM_THREADS=4 OMP_PROC_BIND=false PYTHONPATH=<build> python tests/python/test_balanced_force_restart.py
Exit 0 pass, 1 fail, 77 skipped (no module).

Function Documentation

◆ F()

test_balanced_force_restart.F ( a )

Definition at line 41 of file test_balanced_force_restart.py.

◆ build()