Flow regime
Turbulent
Standards
Fluids: practical mini calculators
Deterministic tools for Reynolds number, friction factor, Darcy pressure drop, and pump power.
Typical fluid properties (around 20°C)
Practical reference values for early-stage calculations.
| Fluid | Density (kg/m³) | Dynamic viscosity (mPa·s) | Note |
|---|---|---|---|
| Water | 998 | 1.0 | 20°C, clean water |
| Air | 1.2 | 0.018 | 1 atm, 20°C |
| Hydraulic oil | 860-900 | 40-80 | Around ISO VG 46 |
| Mineral oil | 830-870 | 10-30 | Light oils |
Mini Tool
Reynolds + Darcy + pump power
Inputs include ρ, μ, D, L, ε and either Q or v. Swamee-Jain is used in turbulent flow.
Reynolds number
95,302
Friction factor f
0.02605
Pressure drop ΔP
118.514 kPa
Pump power P
273.5 W (0.273 kW)
Computed flow rate
0.0015 m³/s
Computed velocity
4.7746 m/s
- Re = (ρ × v × D) / μ
- Laminar: f = 64 / Re
- Turbulent: f = 0.25 / [log10(ε/(3.7D) + 5.74/Re^0.9)]²
- ΔP = f × (L/D) × (ρv²/2)
- P = (ΔP × Q) / η
Typical roughness table
Click a row action to push ε directly into the calculator input.
| Material | ε (mm) | Note | Action |
|---|---|---|---|
| Drawn steel pipe | 0.0015 | Very smooth internal finish | |
| Commercial steel pipe | 0.045 | Common practical assumption | |
| Cast iron pipe | 0.26 | Can be higher in aged systems | |
| PVC / CPVC | 0.0015 | Smooth plastic pipe |
Viscosity unit helper
mPa·s ↔ Pa·s conversion.
References
- ISO 5167: Flow measurement standards
- Crane TP-410: Flow of Fluids Through Valves, Fittings, and Pipe
- White, Fluid Mechanics (Darcy-Weisbach and friction factor chapters)
- Fox & McDonald, Introduction to Fluid Mechanics