Darcy-Weisbach Calculator
Calculate pressure drop and head loss in pipes using the Darcy-Weisbach equation
Pipe Flow Parameters
Total length of the pipe section
Internal diameter of the pipe
Average velocity of fluid flow
Density of the flowing fluid
Darcy friction factor (typically 0.015-0.05 for smooth pipes)
Common Fluid Presets
Darcy-Weisbach Results
Total Pressure Drop
Additional Results
Formula used: ΔP = f × (L/D) × (ρ × V²) / 2
Input values: L=0.00m, D=0.000m, V=0.00m/s, ρ=1000.0kg/m³, f=0.02
Flow Analysis
Example Calculation
Water Pipeline Example
Pipe: 100 m long, 1 m diameter
Fluid: Water (ρ = 1000 kg/m³)
Flow velocity: 10 m/s
Friction factor: 0.03
Calculation
ΔP = f × (L/D) × (ρ × V²) / 2
ΔP = 0.03 × (100/1) × (1000 × 10²) / 2
ΔP = 0.03 × 100 × 100,000 / 2
ΔP = 150,000 Pa = 150 kPa
Friction Factor Guidelines
Smooth Pipes
f = 0.015 - 0.025
New steel, copper, plastic
Medium Roughness
f = 0.025 - 0.035
Cast iron, welded steel
Rough Pipes
f = 0.035 - 0.05+
Old pipes, corroded surfaces
Flow Regimes
Laminar
Re < 2,300
Smooth, layered flow
Transitional
2,300 < Re < 4,000
Unstable flow pattern
Turbulent
Re > 4,000
Chaotic, mixed flow
Calculation Tips
Use the Moody diagram for accurate friction factors
Consider pipe roughness and Reynolds number
Account for temperature effects on fluid properties
Add safety factors for real-world applications
Understanding the Darcy-Weisbach Equation
What is the Darcy-Weisbach Equation?
The Darcy-Weisbach equation is a fundamental formula in fluid mechanics used to calculate pressure loss due to friction in pipes. It relates the pressure drop to pipe geometry, fluid properties, and flow characteristics.
Applications
- •Water distribution systems
- •Oil and gas pipelines
- •HVAC system design
- •Process plant piping
Equation Components
ΔP = f × (L/D) × (ρ × V²) / 2
- ΔP: Pressure drop (Pa)
- f: Darcy friction factor (dimensionless)
- L: Pipe length (m)
- D: Pipe diameter (m)
- ρ: Fluid density (kg/m³)
- V: Flow velocity (m/s)
Note: The friction factor depends on Reynolds number and relative roughness
Friction Factor Determination
Laminar Flow (Re < 2300)
f = 64 / Re
Simple analytical relationship
Turbulent Flow (Re > 4000)
Use Moody diagram or Colebrook equation
Depends on Reynolds number and roughness