VELOCITY AND BOUNDARY SHEAR IN A WIDE COMPOUND DUCT

Mean flow distributions of primary velocity and boundary shear stress were measured in a wide closed duct with a range of asymmetric compoun d cross-sections. The cross-sectional geometries included three differ ent wall angles, vertical, 1:1 and 1:2 (vertical:horizontal) at the in terface between the shallow and deep subsections. Results are presente d for the effect of relative depth and wall angle upon primary velocit y, boundary shear stress and friction factors. The particularly detail ed boundary shear stress measurements indicate the presence of seconda ry flow on the flood plain even at the lowest relative depths, where i t would not normally be identified by coarser spacing of the data.