Turbulent Flow in the Entry Region of a Rough Pipe

General characteristics of mean turbulent flow in the entry region of a pipe were investigated. The development of wall shear stress, velocity profile, core velocity, and boundary layer thickness was studied. A mathematical model for predicting boundary layer growth in developing flow is presented. Momentum and continuity equations were used with assumptions of (1) potential flow in the core region, (2) a semi-log velocity profile for the boundary layer, and (3) a measured resistance formula from the experimental data. Results show that the model can predict satisfactorily within the first 10 to 12 pipe diameters. The experimental data were obtained in a 12-inch diameter hydraulically rough pipe. Turbulence was suppressed and a developing boundary layer was formed by a settling chamber with a converging nozzle. Water was used as the fluid.