InnerLayer.SLAYER - TEST - Verify the two-fluid layer ODE reduces to the Fitzpatrick 2025 Eq. (100) width in the deep diffusive-resistive limit

オープン
  • 何か問題がありますか？
#411 コメント 0 件 リアクション 0 件 担当者 0 名 GitHub で見る

メンテナーはふだん 3 日以内に返信

まだ誰も着手していません。

評価

難易度
5/5
見積もり時間
1週間以上
初心者へのやさしさ
18/100
issue の種類
ドキュメント
明瞭さ
説明が足りない
活発さ
静か
技術スタック
julia
領域
documentation

調査の方向性

Start from InnerLayer.SLAYER: the general two-fluid Riccati width riccati_del_s (book dispersion / small-q limit) versus slayer_dels_fitzpatrick (Fitzpatrick 2025 Eq. 100) and the DIII-D-like harness fixture already in that deep diffusive-resistive corner. Derive or extract a single width definition in the Q̂*, P̂ → 0 limit, explain the ~0.5 factor (or a real model discrepancy), then record it on the workflow docs page / references.md and pin the harness if an identity holds. Done is an explained ratio plus that write-up, not a code patch from this issue alone.

索引モデルが issue の本文から書いたものです。

説明

Motivation

While implementing the layer-overlap truncation (#298), the general two-fluid Riccati width
(riccati_del_s, the 2023 book's model — validated against its figs 6.2/6.3) and the closed-form
diffusive-resistive width of Fitzpatrick 2025 Eq. (100) (arXiv:2511.07666; the width the truncation
criterion is calibrated with) were compared on the DIII-D-like deck. They differ by a near-uniform
factor: Eq. (100) ≈ 0.47–0.59 × the ODE width across m = 2–10, surfaces spanning very different
parameters.

A near-constant ratio suggests a width-definition offset, not a physics disagreement: the ODE width
is defined through the dispersion relation (the equivalent resistive-sheet thickness, book Eq. 6.24,
extracted via the small-q limit of Eq. 6.41), while Eq. (100) is the spatial decay scale of the
layer solution (the |G|^(-1/4) p-space thickness of the paper's Eq. 97, converted to radius).
Those are inequivalent definitions of "width" for the same layer and should differ by a derivable
O(1) constant. But this is currently a hypothesis fit to one deck, and the ~20% drift in the ratio
is unexplained (model differences are plausible: four-field at Q = Q_e vs the paper's three-field
static-RMP response at Q_E + Q_e; compressibility/semi-collisional terms in one and not the other).

The check

In the deep diffusive-resistive corner (book regime map fig 6.1: Q̂*, P̂ → 0), either

  • extract a spatial-decay width from the general Riccati solve (the analogue of |G|^(-ν)), or
  • derive the book model's DR asymptote analytically,

and compare against Eq. (100) under a single width definition. The DIII-D 2/1 surface sits in that
corner (Q̂ ≈ 0.007, P̂ ≈ 0.009), so the existing slayer_dels_fitzpatrick harness fixture covers
the right parameter range for a regression pin once the constant is derived.

Acceptance

  • The ratio is explained by a derived constant (with the residual drift attributed), or a real model
    discrepancy is identified and its consequence for the truncation criterion stated.
  • The result is recorded where the two widths are documented (workflow docs page /
    references.md one-liner), and pinned in the harness if a clean identity exists.

Why it matters

The truncation criterion (#298) uses Eq. (100) because the paper's ε_c values and its fig 9
cross-validation are calibrated in that convention. On the DIII-D deck the factor ~2 between the two
widths is exactly the difference between truncating at ψ = 0.9971 (keep q ≤ 6) and ψ = 0.9892
(keep q ≤ 5), so knowing whether the offset is definitional or physical bounds the systematic
uncertainty of the domain choice. Not a blocker for #298.

主要言語
Julia
スター
11
フォーク
7
平均マージ
4日 3時間
マージ済み PR（30日）
70

環境構築

  • Dockerfile・Docker Compose ファイルなし
  • プルリクエストのテンプレートあり
  • コントリビューションガイドなし

はじめの一歩

  1. issue を最後まで読み、次にプロジェクトのコントリビューションガイドを読みます。
  2. 着手することを issue にコメントします — 二人が同じ作業をするのを防げます。
  3. リポジトリをフォークし、ブランチを切って変更します。
  4. issue 番号を参照したプルリクエストを送ります。

OpenFUSIONToolkit/GPEC のほかの issue

OpenFUSIONToolkit/GPEC の issue をすべて見る

似ている issue

Julia の issue をもっと見る

新しい issue をメールで受け取る

初心者向けの GitHub issue を短くまとめたダイジェスト。