Determining Friction Factors in Turbulent Pipe Flow

Head loss due to friction for fluids traveling through pipes, tubes and ducts is a critical parameter for solving turbulent-flow problems in the chemical process industries. The Colebrook equation is used to assess hydraulic resistance for turbulent flow in both smooth- and rough-walled pipes. The equation contains a dimensionless fluid-flow friction coefficient that must be calculated for the properties of the pipe and the fluid flow. Determining friction factors for the Colebrook equation requires either calculating iteratively or manipulating the equation to express friction factors explicitly. Iterative calculations can be carried out using a spreadsheet solver, but can require more computational time. Explicit expressions offer direct computation, but have a range of simplicity and corresponding error. The Lambert W function may be a better method to express friction factors explicitly because it allows users to avoid iterative calculation and also reduce relative error. This article outlines methods for determining friction factors, and discusses how to use the Lambert W function. The Lambert W function is evaluated using real data in Part 2 of the feature. Colebrook equation Pipe-flow problems are challenging because they…