Darcy Weisbach Equation
The Darcy Weisbach Equation for calculating the pipe losses is as below;
In the Darcy–Weisbach Equation, the friction factor f can be calculated from the equation of Colebrook–White.
where k is the absolute roughness of the pipe wall (mm), D the inner diameter of the pipe (mm) and Re the Reynolds number .
To avoid iterative calculation, Barr (1975) suggests the following acceptable approximation, which deviates from the results obtained by the Colebrook–White Equation for 1%:
The Reynolds number describes the flow regime. It can be calculated as:
where ν (m2/s) stands for the kinematic viscosity. This parameter depends on the water temperature and can be determined from the following equation:
Where, T is temperature in Degree Centigrade.