pipe-flow-reynolds

Internal (pipe) flow calculations, done properly and without dependencies:

• Reynolds number and laminar / transitional / turbulent regime
• Darcy friction factor
  • laminar 64/Re
  • Haaland explicit approximation (no iteration)
  • full Colebrook–White solved iteratively (seeded from Haaland)
• Darcy–Weisbach head loss and pressure drop
• volumetric flow rate for a circular pipe

Everything is SI. nu is kinematic viscosity (m²/s); if you only have dynamic viscosity mu (Pa·s) and density, use reynoldsFromDynamic.

Quick start

const pf = require('pipe-flow-reynolds');

// Water, 2 m/s in a 50 mm pipe (nu ≈ 1e-6 m²/s)
const Re = pf.reynolds(2, 0.05, 1e-6);   // 1e5
pf.regime(Re);                           // 'turbulent'

// commercial steel, eps/D ≈ 1e-4
const f = pf.frictionFactor(Re, 1e-4);   // ~0.0185 via Colebrook

// pressure drop over 100 m
pf.pressureDrop(f, 100, 0.05, 2, 1000);  // Pa

Friction factor

frictionFactor(Re, relRoughness) picks the right correlation for you: 64/Re below Re = 2300, Colebrook–White otherwise. If you specifically want one method:

pf.laminarFriction(2000);           // 0.032
pf.haalandFriction(1e5, 1e-4);      // explicit, ~2% of Colebrook
pf.colebrookFriction(1e5, 1e-4);    // iterated, tight tolerance

relRoughness is the relative roughness eps/D (dimensionless). Pass 0 for a hydraulically smooth pipe.

Transitional flow (2300 < Re < 4000) has no reliable single correlation. frictionFactor uses the turbulent branch there; treat the result with care.

License

MIT