Observations on Flow around Bridge Abutment

Results are presented from an experimental investigation into the skewed threedimensional flow around a bridge abutment. Velocity profiles on the plane of symmetry matched the standard log-law only near the bed and revealed a rather uniform flow in the upper layer. The bed shear stress was found to amplify nearly 3.63 times near the nose of the abutment. The flow was deflected least at the midwater depth, exceeded slightly by the upper flow and substantially by the lower flow. The flow was also analyzed using the theories of three-dimensional turbulent boundary layers. None of the crossflow models matched the data. The performance of near-wall similarity models was also poor. However, strong evidence of near-wall similarity was found very near to the bed. Compared to the bridge pier flow, greater skewing was found in abutment flow, especially in the downstream region, showing the limitations of treating the abutment as a half-pier.