Error Analysis of Friction Factor Formulae with Respect to Colebrook-White Equation

An important and integral part of pressure drop in a pipe involves the determination of friction factor. The DarcyWeisbach friction factor formula is used for calculation of pressure loss in pipes. The ColebrookWhite (C-W) equation gives the best approximation to Darcy Weisbach friction factor for turbulent flow. C-W equation cannot be solved directly due to its implicit form. Several numbers of approximate explicit equations have been proposed by many investigators. A brief review on friction factor formulae is presented. The study is to select a suitable friction factor formula in order to use it in pipe flow study for the calculation of friction factor. Thus an analysis is done to compare the percentage error of friction factor correlations. Based on applicability range of Reynolds number and pipe roughness, few equations are chosen. Relative percentage error of these selected approximate resistance equations are evaluated against the full range of flow conditions at different roughness sizes and found that average percentage error by Fangs (2011) and Romeos (2008) equations are quite low in comparison to the others. Moreover it gives significantly better result than the commonly used equation of Barr (1981). Thus field engineer may use any one of the above explicit equations in the computation of friction factor value.