Shear Stress Distribution in Partially Filled Pipes

Boundary shear stresses have been calculated for circular pipes with a flat sediment bed using computational fluid dynamics (CFD). First of all, CFD simulations were carried out for rectangular channels in order to check the software package for its ability to reproduce experimental (literature) results. The influence of the applied turbulence model (isotropic or anisotropic) was also studied for rectangular channels. The simulations for circular pipes, using an isotropic turbulence model, were done for different filling ratios, mean flow velocities, and roughness heights. For validation, the numerical results were compared with former experimental work. With the help of the detailed shear stress distribution, sediment transport can be calculated more accurately than using the global shear stress, as is traditionally done. This method was applied to a simple flume experiment, subjected to a triangular inflow hydrograph, and the comparison with the traditional approach was made.