Explicit approximation to the Colebrook-White equation — no iteration required. Includes comparison with the exact CW result.
Pipe Networks · FrictionSwamee-Jain Formula (explicit, single evaluation)
Colebrook-White Reference (implicit, iterated)
Darcy vs Fanning Friction Factor
Typical Pipe Roughness
| Material | ε (m) | ε (mm) |
|---|---|---|
| PVC / glass / drawn tubing | 1.5×10⁻⁶ | 0.0015 |
| Commercial steel | 4.6×10⁻⁵ | 0.046 |
| Galvanized steel | 1.5×10⁻⁴ | 0.15 |
| Cast iron | 2.6×10⁻⁴ | 0.26 |
| Concrete | 1×10⁻³ | 1.0 |
Swamee-Jain gives explicit results without iteration, making it ideal for hand calculations and initial estimates. When computational cost is not a concern, Colebrook-White gives the more accurate reference answer.