Darcy Friction Loss
Compute Darcy friction head loss hf from f, length L, dia. D and velocity v.
Inputs
Formula
hf = f·(L/D)·v²/(2g), g=9.81
Get f from the Moody chart or Colebrook.
Fundamentals
Compute Darcy friction head loss hf from f, length L, dia. D and velocity v.
This tool computes Darcy Friction Loss from the formula: hf = f·(L/D)·v²/(2g), g=9.81
History
Fluid mechanics and heat transfer were established in the 18th–19th centuries with steam engines and thermodynamics.
Engineering applications
Used for piping, heat-exchange and hydraulic system estimates.
Glossary
| Friction coeff. f | Input parameter |
| Length L | Input parameter |
| Dia. D | Input parameter |
| Head loss hf | Output result |
How to use
- Fill in Friction coeff. f, Length L, Dia. D, Velocity v in the Inputs section (watch the unit on each field).
- Click Calculate; the tool evaluates the formula shown above.
- Read Head loss hf in the results area.
Formula · Worked Example · Knowledge
Formula
核心计算关系：hf = f·(L/D)·v²/(2g), g=9.81
输入变量：
- Friction coeff. f
f - Length L
L— m - Dia. D
D— m - Velocity v
v— m/s
输出结果：
- Head loss hf
hf— m
假设/适用：Flow formulas assume steady, incompressible, continuous flow; correct for compressible/high-speed.
Worked Example
根据公式 hf = f·(L/D)·v²/(2g), g=9.81，取 Friction coeff. f = 0.02；Length L = 50 m；Dia. D = 0.05 m；Velocity v = 2 m/s。
代入计算得：Head loss hf = 4.077 m。
Key Points
- Flow formulas assume steady, incompressible, continuous flow; correct for compressible/high-speed.
- Reynolds Re sets laminar/turbulent; friction f depends on regime & roughness.
- Energy eqn includes elevation, pressure and velocity heads; keep units as length.
Parameters
Inputs
| Parameter | Symbol | Unit | Default |
|---|---|---|---|
| Friction coeff. f | f | 0.02 | |
| Length L (m) | L | m | 50 |
| Dia. D (m) | D | m | 0.05 |
| Velocity v (m/s) | v | m/s | 2 |
Outputs
| Result | Symbol | Unit |
|---|---|---|
| Head loss hf | hf | m |
Applications
- Pipe flow rate and pressure drop
- Hydraulic cylinder force/speed design
- Flow-meter selection and calibration
FAQ
What formula does this tool use?
This tool computes per ISO / AGMA / ASME standard formulas: hf = f·(L/D)·v²/(2g), g=9.81
How accurate are the results?
Results match input precision, based on SI units and common engineering approximations; for critical duty re-check with a safety factor.
Where is it used?
Pipe flow rate and pressure drop