Hydraulic resistance in part-full pipes with composite roughness

The paper discusses the boundary shear stresses and the hydraulic resistance in part-full sewer pipes with composite roughness. The discussion is based on a series of numerical experiments using a validated numerical turbulence model. The results from the numerical model are compared with the sidewall elimination method. It is concluded that the numerical model reproduces well the boundary shear in part-full pipes and that the difference between the two methods is of the order 5% in items of bed shear stress