PyREC scaffolding (from YREC development, 7be4133)/ checkj.fGlossary

checkj.f

404 lines · 1 definitions · on GitHub (7be4133)

Python version: checkj.py, 303 lines, on the right (switch to Python above the code).

Variables on this page (26)

acfpft, chi, djok, echi, ecod3, ecod4, hle, imodpt, ishort, itdif2, json, ldifad, nprtpt, ntot, rat, sr, toleri, ves, ves0, vesa, vesd, vgsf, vgsf0, vmu, vss, wold

Purpose

This file checks each iteration of angular-momentum transport. Its header lists five tasks: catch negative specific angular momentum $j = J/M$; test convergence of the iteration on the diffusion coefficients; compute $\Omega$ (and the moment of inertia) from the new $j$; remove reversals of the $\Omega$ gradient by imposing solid-body rotation locally; and print details.

How it fits

  • Inputs: the arguments, the model (HD, HR, HS, HS2, LCZ), HJM ($j$ after this iteration), HJMP ($j$ after the previous iteration), HJMSAV ($j$ at the start of the step), IT, LOKAD; DJOK, ITDIF2 (which also sizes the per-iteration history DELJI, IMAXI) from NMLPAR_MOD; WOLD ($\Omega$ of the previous model) from OLDROT_MOD; TOLERI (ERRMOM_MOD) and ACFPFT (NMLPAR_MOD), the tolerances of the moment-of-inertia iteration.
  • Who calls it: SECULR.
  • What it calls: GETROT ($\Omega$, moment of inertia $I$ and $\partial I/\partial\Omega$ from $j$) and SOLID (solid-body rotation over a range of shells).
  • Outputs: OMEGA, HI, QIW, ETA2, R0, HJMP (set to HJM), LOK, LREDO, DT, IREDO.
  • Modules: TEMP2_MOD, QUADD_MOD, EGRID_MOD, DIFAD_MOD, DIFAD2_MOD, and from NMLPAR_MOD NPRTPT and LDIFAD, are used only in the detailed print, which is now switched off (see Design).

The method

  1. If $j \le 0$ anywhere, stop with exit status 1. The branch that would halve the time step instead (lines 160–167↗) never runs (unused?).

  2. Convergence: $\delta_\mathrm{it} = \max_i |j_i - j_i^\mathrm{prev}|/j_i^\mathrm{prev}$; converged (LOK) if $\delta_\mathrm{it} \le$ DJOK. If LOKAD is set on entry, LOK starts true.

  3. $\Omega$ from $j$: call GETROT. Before the last iteration and while not converged, the tolerances TOLERI and ACFPFT are relaxed to $\max(10^{-2}\,\mathrm{DJOK}, \text{tolerance})$, "because the error in the diffusion is of order DJOK," and restored after.
  4. Gradient reversals: from the surface inward, where $\Omega_i - \Omega_{i-1}$ is positive (by more than $10^{-15}$) but was not positive in the previous model (WOLD), mix the two shells (and any adjacent convection zone) to solid-body rotation with SOLID; then widen the range while the boundaries show new reversals.
  5. Print at the last iteration or on convergence: the largest $\Delta j/j$ over the step, and $\delta$ of each iteration.

Design

The detailed output to IMODPT is switched off by IF(.TRUE.)GOTO 240 (G. Somers 11/14: "this can be trivially extracted from the extended .STORE file"), so more than 60 lines below it never run (lines 326–401↗; unused?, with the modules only they need).

From YREC's documentation

Physics Options: DJOK (default 1.0D-4) is the numerical tolerance of rotational mixing; ITDIF2 (1) the number of iterations between nuclear burning and rotational mixing (1 = none). Control Options: NPRTPT writes details for every NPRTPT-th point. The per-shell file FMODPT is "no longer used"; CHECKJ's writes to it are skipped (IF(.TRUE.)GOTO 240), though PARMIN still opens it.

Definitions

subroutineCHECKJ

lines 3–404 · GitHub

Checks one iteration of angular-momentum diffusion: stops on $j \le 0$, tests convergence against DJOK, gets $\Omega$ from $j$ (GETROT), and removes $\Omega$-gradient reversals with SOLID.

Uses modules DIFAD2_MOD, DIFAD_MOD, DIMENSIONS_MOD, EGRID_MOD, ERRMOM_MOD, IOUNITS_MOD, NMLPAR_MOD, OLDROT_MOD, QUADD_MOD, TEMP2_MOD

Called by SECULR

Flowchart of its calls, in order (3)
GETROT201
repeated from label 20 (GO TO at line 295), lines 208–295
if (OMEGA(I)-OMEGA(I-1).GT.1.0D-15), lines 213–290
SOLID244
if (LREDO), lines 282–286
SOLID283

Change log

The changes since rp_1

Changed since rp_1. Declarations only: COMMON blocks to modules, IMPLICIT NONE.

Changed since a8a5950. The reversal search enters at $\Omega_i - \Omega_{i-1} > 10^{-15}$ rad s$^{-1}$ instead of 1 (settles former question 2); DELJI and IMAXI are SAVEd allocatable arrays sized $\max(\mathrm{ITDIF2}, \mathrm{IT}, 1)$ instead of 16 (settles former question 3); the stop on $j \le 0$ is STOP 1 (KNOWN_ISSUES.md, issue 38).