Source: https://guthlabs.ai/docs/instruments/reynolds-number-for-blood-flow-biofluid-mechanics/implementation/

instrument implementation / implementation-contract

# Reynolds Number for Blood Flow (biofluid mechanics) implementation

A source-bound implementation contract for Reynolds Number for Blood Flow (biofluid mechanics); 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**: t7-102

**Effect**: Computation or source lookup only

## Input and validation requirements

The instrument breaks on zero viscosity because the Reynolds-number calculation is undefined and must be rejected. It also has a convention hazard for signed velocity and a classification discontinuity at the Re = 2300 regime threshold.

## 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": {
    "vessel_diameter": 0.004,
    "diameter_unit": "m",
    "flow_velocity": 0.5,
    "velocity_unit": "m/s",
    "blood_density": 1060,
    "density_unit": "kg/m^3",
    "blood_viscosity": 0.0035,
    "viscosity_unit": "Pa·s",
    "temperature_C": 37
  },
  "expected_outputs": {
    "reynolds_number": 605.7142857143,
    "flow_regime": "laminar"
  },
  "reference_data": {
    "blood_density_kg_m3_at_37C": {
      "value": 1060,
      "source_convention": "widely tabulated standard value (human-blood physiology/hemodynamics textbook convention)"
    },
    "blood_dynamic_viscosity_Pa_s_at_37C": {
      "value": 0.0035,
      "source_convention": "widely tabulated standard value (human-blood physiology/hemodynamics textbook convention)"
    },
    "regime_thresholds": {
      "laminar": "Re < 2000",
      "transitional": "2000 <= Re <= 4000",
      "turbulent": "Re > 4000",
      "source_convention": "widely tabulated standard engineering convention"
    }
  },
  "working": "Re = ρvd/μ\n= (1060 kg/m^3 × 0.5 m/s × 0.004 m) / 0.0035 Pa·s\n= 2.12 / 0.0035\n= 605.7142857143.\nSince 605.7142857143 < 2000, the label is laminar."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/reynolds-number-for-blood-flow-biofluid-mechanics/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/reynolds-number-for-blood-flow-biofluid-mechanics/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/reynolds-number-for-blood-flow-biofluid-mechanics/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-tranche7/tranche7-results.json`