1. What is the Colebrook-White Equation?

The Colebrook-White equation is an implicit equation that relates the friction factor in pipe flow to the Reynolds number and relative roughness. It provides an accurate estimation of friction losses in turbulent flow through rough pipes.

2. How Does the Calculator Work?

The calculator uses the Colebrook-White equation:

Where:

• \( f \) — Darcy-Weisbach friction factor (dimensionless)
• \( \varepsilon \) — Absolute roughness of pipe (m)
• \( D \) — Pipe diameter (m)
• \( Re \) — Reynolds number (dimensionless)

Explanation: The equation is solved iteratively since it's implicit in the friction factor. The calculator uses an iterative numerical method to converge to the solution.

3. Importance of Friction Factor Calculation

Details: Accurate friction factor calculation is crucial for determining pressure drops in piping systems, designing efficient fluid transport systems, and optimizing energy consumption in industrial applications.

4. Using the Calculator

Tips: Enter pipe roughness in meters, pipe diameter in meters, and Reynolds number (dimensionless). All values must be positive. The calculator automatically solves the implicit equation using numerical iteration.

5. Frequently Asked Questions (FAQ)

Q1: What flow regimes does Colebrook-White apply to?
A: The equation applies to turbulent flow in rough pipes (Re > 4000) and is valid for the complete turbulent regime.

Q2: Why is the equation implicit?
A: The friction factor appears on both sides of the equation, making it impossible to solve explicitly. Numerical methods are required for solution.

Q3: What are typical roughness values?
A: Commercial steel: 0.045 mm, Cast iron: 0.26 mm, Concrete: 0.3-3.0 mm, Drawn tubing: 0.0015 mm.

Q4: Are there explicit approximations available?
A: Yes, the Haaland equation and Swamee-Jain equation provide explicit approximations with good accuracy for most engineering applications.

Q5: When is Colebrook-White not applicable?
A: The equation is not valid for laminar flow (Re < 2000) or for extremely smooth pipes where molecular effects dominate.