Experimental study of the effect of changes in U/Uc on scour hole around vertical-inclined piers in various positions of a sharp 180-degree bend

This research investigated scour patterns near vertical and inclined piers in a laboratory flume with a sharp 180° flume. The investigation focused on parameters such as the shape of the pier group, direction, and installation position under various flow conditions to analyze the scouring pattern and sedimentation. The findings revealed that the greatest depth of scour and sedimentation height occurred around the vertical and converging pier group at the 60-degree position under live bed conditions, reaching 128% and 88% of the flow depth, respectively. By relocating divergent-vertical pier groups from the 60-degree to the 90-degree position, the deepest scour increased by 20% under the clear water conditions, while under incipient motion conditions, relocating pier from 60-degree to the 90-degree position, resulted in an 8% reduction in the deepest scour. Additionally, relocating the divergent-vertical pier groups from the 60-degree to the 120-degree position under live bed conditions led to an approximately 13% reduction in maximum scour depth. Moreover, increasing the average flow velocity over the critical velocity ratio of bed particles (U/Uc) led to a rise in the scour hole volume for both convergent and divergent pier groups positioned at 60°, 90°, and 120°.