# 📐 L2 Spec — Boundary Layer — Prandtl / Blasius near-wall flow Mismatch-Only Spec
**ID:** `L2-174-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-174`](/artifact/l1/L1-174)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41553969
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| N y | — | 32 – 10000 |
| Re x | — | 100.0 – 10000000000.0 |
| Snr db | dB | 0 – 40 |
| Re x error | — | 0.0 – 0.1 |
| Roughness error | — | 0.0 – 0.3 |
| Pressure gradient error | — | 0.0 – 0.3 |
## 2. Tolerance (ε)
**Type:** `fn`
```
18.0 + 0.3*SNR_dB - 15.0*Re_x_error - 10.0*pressure_gradient_error - 5.0*roughness_error
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`082fe02d915436eaeb8fa37651314ebb15f6e01e91fa1b56e379977c9a3dfc86`
## 5. On-chain Registration
- **Chain hash:** `0x18334803949bc90dd128074b9fa9cc307898291313eaff0644c1a910853fca4f`
- **Chain tx hash:** `0xb13ff5f031ce6a62743352ca995dc345377d69bd0782da4ae574d62926fe4537`
- **Chain block:** `41553969`
---
## File Mapping
This bundle consists of: `L2-174-001.md`, `L2-174-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-174-001.md` | Source of truth — edit this | Human or LLM |
| `L2-174-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |
**Prompt for your LLM after editing this Markdown:**
> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.
_This Markdown was auto-synthesized from the catalog row for `L2-174-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._