Source: https://guthlabs.ai/docs/instruments/colebrook-white-moody-friction-factor-solver/implementation/

instrument implementation / implementation-contract

# Colebrook-White / Moody Friction Factor Solver implementation

A source-bound implementation contract for Colebrook-White / Moody Friction Factor Solver; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t6-035

**Effect**: Computation or source lookup only

## Input and validation requirements

The Re = 0 input makes both the laminar formula and the Colebrook term undefined and must be rejected. In addition, the specification does not state the laminar/transitional/turbulent thresholds or how the transitional interval is handled, and it does not explicitly distinguish Darcy from Fanning conventions beyond the equation itself.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "Re": 2000,
    "relative_roughness": "0.001",
    "method": "laminar",
    "newton_tolerance": 1e-10
  },
  "expected_outputs": {
    "friction_factor": 0.032,
    "flow_regime": "laminar"
  },
  "working": "Re=2000<2300, so use f=64/Re. 64/2000=0.032 exactly. The roughness is ignored for the laminar formula."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/colebrook-white-moody-friction-factor-solver/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/colebrook-white-moody-friction-factor-solver/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/colebrook-white-moody-friction-factor-solver/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche6/tranche6-results.json`