Biot Number / Lumped Capacitance Validity Check mechanism

Model scope

Formula and threshold are conditionally standard, but the instrument needs an explicit definition or required input convention for Lc, preferably Lc = volume/surface area for the body under analysis. The honest label should state that PASS means Bi < 0.1 under the selected geometry and property assumptions, not that lumped capacitance is universally accurate.

• Bi = hLc/k is the standard Biot-number formula when Lc is the appropriate characteristic length, commonly V/A for lumped-capacitance analysis.
• The validity rule is correctly stated as Bi < 0.1, but the specification does not define how Lc is obtained from body geometry; using a different length convention can change the result.
• The output flag should explicitly define that Bi = 0.1 is FAIL because the stated criterion is a strict inequality.

Units and conventions

• h is in W/(m^2·K).
• Lc is in m.
• k is in W/(m·K).
• Temperature units cancel, so K and °C temperature differences are equivalent in this ratio.
• h, Lc, and k must describe the same physical body and operating temperature range.
• k must be positive; material thermal conductivity may vary with temperature.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "h": 25,
    "Lc": 0.01,
    "k": 0.5,
    "units": "h in W/(m^2·K), Lc in m, k in W/(m·K)"
  },
  "expected_outputs": {
    "Bi": 0.5,
    "valid": "FAIL"
  },
  "working": "Bi = hLc/k = (25 × 0.01) / 0.5 = 0.25 / 0.5 = 0.5. Since 0.5 is not less than 0.1, valid = FAIL."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A zero thermal-conductivity input causes division by zero and an undefined Bi unless explicitly rejected. A separate convention ambiguity can also change the validity result from pass to fail.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json