Functions
	bed_sdf (N, npz)

	make ()

	march (s, cap=CAP)

	diag (s, tag, steps)

Variables
	BED = os.environ["BED"]

	N = int(os.environ.get("N", "96"))

	TOL = float(os.environ.get("MARCH_TOL", "1e-8"))

	CAP = int(os.environ.get("MARCH_MAX", "6000"))

	DT = float(os.environ.get("DT", "60.0"))

	KIND = os.environ.get("KIND", "gauge-exact")

	MU

	F0

	sdf

	R

float	fluid = 0.0

	flush

	sA = make()

	stA = march(sA)

	kA

	UA

	rng = np.random.default_rng(7)

list	pert

	stP = march(sA)

	kP

	_

	sB = make()

	plug = np.asfortranarray(np.where(fluid, float(np.abs(UA[0][fluid]).mean()), 0.0))

	z = np.zeros_like(plug)

	stB = march(sB)

	kB

Detailed Description

Neutral-mode probe: is the collocated march's stalled state an ATTRACTOR or a FROZEN defect?

The steady Stokes step map is linear with a unique true fixed point (phi = 0).  The measured
stalled states (|uf-halfavg(u)| ~ 4e-2 <u>, k off by the plateau) can only be exactly stationary
if the map has (near-)neutral modes; then the reached state depends on the initial condition and
on any perturbation applied along the way.  Test: march from IC-A (zero velocity, the protocol
IC), then (1) perturb the converged state with a small random solenoidal-ish kick and re-march,
(2) march independently from IC-B (a bulk plug profile).  Attractor => all k agree to march
noise.  Neutral modes => they differ at the plateau scale.

  SDFLOW_BUILD=build_omp3 BED=...npz N=96 python collocated_neutral_probe.py

Function Documentation

◆ bed_sdf()

collocated_neutral_probe.bed_sdf	(	N,
		npz
	)

Definition at line 32 of file collocated_neutral_probe.py.

◆ make()

collocated_neutral_probe.make ( )

Definition at line 59 of file collocated_neutral_probe.py.

◆ march()

collocated_neutral_probe.march	(	s,
		cap = `CAP`
	)

Definition at line 75 of file collocated_neutral_probe.py.

◆ diag()

collocated_neutral_probe.diag	(	s,
		tag,
		steps
	)

Definition at line 87 of file collocated_neutral_probe.py.

Variable Documentation

◆ BED

collocated_neutral_probe.BED = os.environ["BED"]

Definition at line 23 of file collocated_neutral_probe.py.

◆ N

collocated_neutral_probe.N = int(os.environ.get("N", "96"))

Definition at line 24 of file collocated_neutral_probe.py.

◆ TOL

collocated_neutral_probe.TOL = float(os.environ.get("MARCH_TOL", "1e-8"))

Definition at line 25 of file collocated_neutral_probe.py.

◆ CAP

collocated_neutral_probe.CAP = int(os.environ.get("MARCH_MAX", "6000"))

Definition at line 26 of file collocated_neutral_probe.py.

◆ DT

collocated_neutral_probe.DT = float(os.environ.get("DT", "60.0"))

Definition at line 27 of file collocated_neutral_probe.py.

◆ KIND

collocated_neutral_probe.KIND = os.environ.get("KIND", "gauge-exact")

Definition at line 28 of file collocated_neutral_probe.py.

◆ MU

collocated_neutral_probe.MU

Definition at line 29 of file collocated_neutral_probe.py.

◆ F0

collocated_neutral_probe.F0

Definition at line 29 of file collocated_neutral_probe.py.

◆ sdf

collocated_neutral_probe.sdf

Definition at line 55 of file collocated_neutral_probe.py.

◆ R

collocated_neutral_probe.R

Definition at line 55 of file collocated_neutral_probe.py.

◆ fluid

float collocated_neutral_probe.fluid = 0.0

Definition at line 56 of file collocated_neutral_probe.py.

◆ flush

collocated_neutral_probe.flush

Definition at line 105 of file collocated_neutral_probe.py.

◆ sA

collocated_neutral_probe.sA = make()

Definition at line 108 of file collocated_neutral_probe.py.

◆ stA

collocated_neutral_probe.stA = march(sA)

Definition at line 109 of file collocated_neutral_probe.py.

◆ kA

collocated_neutral_probe.kA

Definition at line 110 of file collocated_neutral_probe.py.

◆ UA

collocated_neutral_probe.UA

Definition at line 110 of file collocated_neutral_probe.py.

◆ rng

collocated_neutral_probe.rng = np.random.default_rng(7)

Definition at line 113 of file collocated_neutral_probe.py.

◆ pert

list collocated_neutral_probe.pert

Initial value:

=  [np.asfortranarray(np.where(fluid, 0.1 * np.abs(UA[0][fluid]).mean()
                                   * rng.standard_normal(UA[a].shape), 0.0))
        for a in range(3)]

Definition at line 114 of file collocated_neutral_probe.py.