Enter the relative roughness and the Reynolds number into the calculator to determine the friction factor using the Haaland equation. This calculator helps in estimating the friction factor for flow in a pipe or duct.

## Haaland Equation Formula

The Haaland equation is used to calculate the friction factor for fluid flow in a pipe. The formula is as follows:

f = ( {1}{-1.8 c* log_{10}(({epsilon}{D})^{1.11} + {6.9}{Re})} )^2

Variables:

• f is the Darcy-Weisbach friction factor
• ε/D is the relative roughness of the pipe
• Re is the Reynolds number, a dimensionless quantity representing the ratio of inertial forces to viscous forces

To calculate the friction factor, input the relative roughness and the Reynolds number into the Haaland equation.

## What is the Haaland Equation?

The Haaland equation is an empirical formula that provides an approximation for the Darcy-Weisbach friction factor for turbulent flow in smooth and rough pipes. It is a simplified version of the more complex Colebrook-White equation and is known for its ease of use and reasonable accuracy for a wide range of conditions.

## How to Calculate Friction Factor using the Haaland Equation?

The following steps outline how to calculate the friction factor using the Haaland Equation.

1. First, determine the relative roughness of the pipe (ε/D).
2. Next, determine the Reynolds number (Re).
3. Use the Haaland equation to calculate the friction factor (f).
4. Insert the values into the equation and solve for the friction factor.
5. Use the calculator above to verify your results.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Relative roughness (ε/D) = 0.0005

Reynolds number (Re) = 100000