Calculator · Fluid Mechanics
Darcy Friction Factor Calculator
Anemodia reports the Darcy friction factor f_D, the factor that appears directly in Darcy–Weisbach. The Fanning factor is a different convention, f_D = 4 f_F, and the two are never mixed.
Inputs
Results
Darcy friction factor f_D
Colebrook–White, solved as a bracketed root.
| Reynolds number Re | 100000 |
|---|---|
| Relative roughness ε/D | 0.001 |
| Flow regime | Turbulent |
| Darcy friction factor f_D | 0.0221745 |
| Fanning factor f_F = f_D/4 | 0.00554363 |
| Colebrook residual | 3.27e-11 |
| Iterations | 36 |
Assumptions
- · Fully developed flow in a pipe of uniform roughness.
- · Darcy friction factor; f_D = 4 f_F.
Explore in the Lab
The Lab computes Re and f_D for each segment from the same engine.
Technical reference
laminar: f_D = 64/Re
turbulent: 1/√f_D = −2 log₁₀( ε/(3.7 D) + 2.51/(Re √f_D) )
f_D = 4 f_F
- f_D
- Darcy friction factor[-]
- f_F
- Fanning friction factor[-]
- Re
- Reynolds number[-]
- ε/D
- relative wall roughness[-]
Re < 2300 laminar, 2300 ≤ Re < 4000 transitional, Re ≥ 4000 turbulent. These are conventional engineering boundaries for internal pipe flow, not exact physical discontinuities.
In the transitional range no correlation gives an exact friction factor; the value returned there is an estimate and is flagged as one.
Reference cases: Re = 1000 gives f_D = 0.064; Re = 100000 with ε/D = 0.001 gives f_D ≈ 0.0222.