# 📐 L2 Spec — Lattice Boltzmann Method (LBM) — mesoscale fluid Mismatch-Only Spec
**ID:** `L2-187-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-187`](/artifact/l1/L1-187)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41553979
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 32 – 4096 |
| W | px | 32 – 4096 |
| Z | — | 8 – 1024 |
| Snr db | dB | 0 – 40 |
| N times | — | 100 – 1000000 |
| Grid error | — | 0.0 – 0.3 |
| Compressibility error | — | 0.0 – 0.2 |
| Relaxation time error | — | 0.0 – 0.2 |
## 2. Tolerance (ε)
**Type:** `fn`
```
16.0 + 0.3*SNR_dB - 20.0*relaxation_time_error - 10.0*grid_error - 15.0*compressibility_error
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`dcb6fcbcb47aa2c1e57bdbf11849b6d4db702ce059b3ad33fd6ecbc3200f687a`
## 5. On-chain Registration
- **Chain hash:** `0x5df89d8b39828aab93cb21229e6c1dd3007e62175f5eb2d513eb3423e9b4b51a`
- **Chain tx hash:** `0xe6ccf27e86a9b8d7c5824fc85a6235d52cadeed4dec25f1ba2709163d845180e`
- **Chain block:** `41553979`
---
## File Mapping
This bundle consists of: `L2-187-001.md`, `L2-187-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-187-001.md` | Source of truth — edit this | Human or LLM |
| `L2-187-001.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 `L2-187-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._