Reynolds Number for Blood Flow (biofluid mechanics) mechanism

Model scope

The arithmetic formula is correct under the stated SI assumptions, but the instrument needs an explicit regime-threshold convention, a defined velocity type, and clearer preset provenance before it can be treated as fully specified. The density 1060 kg/m^3 and viscosity 3.5 mPa·s values are exact widely tabulated human-blood textbook presets used in all four vectors.

• Re = ρvd/μ is the standard Reynolds-number formula for a Newtonian fluid when ρ, v, d, and μ are in mutually consistent units.
• The flow-regime algorithm is underspecified: no thresholds or treatment of the boundary values are provided. These test vectors use the common convention Re < 2000 = laminar, 2000 ≤ Re ≤ 4000 = transitional, and Re > 4000 = turbulent.
• Blood is non-Newtonian and flow is often pulsatile; using one fixed viscosity is an educational approximation and may not represent an apparent viscosity for a particular vessel, shear rate, temperature, or hematocrit.
• The specification does not define whether velocity means mean cross-sectional velocity, peak velocity, or another velocity measure. Reynolds number normally uses mean velocity for the stated vessel diameter.

Units and conventions

• All calculations use SI units: density in kg/m^3, velocity in m/s, diameter in m, and dynamic viscosity in Pa·s.
• The standard preset values used here are human-blood density 1060 kg/m^3 and dynamic viscosity 3.5 mPa·s = 0.0035 Pa·s at approximately 37 °C.
• Diameter must be a vessel's internal diameter, not radius or external diameter.
• For regime labels, the convention used is laminar below Re 2000, transitional from Re 2000 through Re 4000 inclusive, and turbulent above Re 4000.

Inspectable vector

One of 4 source-bound review vectors:

{
  "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."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

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.

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-tranche7/tranche7-results.json
• BOUNDARY_HAZARD_CATALOG.json