Velocity and boundary shear in a wide compound duct

Abstract

Mean flow distributions of primary velocity and boundary shear stress were measured in a wide closed duct with a range of asymmetric compound cross-sections. The cross-sectional geometries included three different wall angles, vertical, 1:1 and 1:2 (vertical:horizontal) at the interface between the shallow and deep subsections. Results are presented for the effect of relative depth and wall angle upon primary velocity, boundary shear stress and friction factors. The particularly detailed boundary shear stress measurements indicate the presence of secondary flow on the flood plain even at the lowest relative depths, where it would not normally be identified by coarser spacing of the data.