Characteristics of flow around a cylindrical pier under a partially submerged bridge deck

This study investigated flow characteristics around a cylindrical pier under a partially submerged bridge deck. The tests were carried out in clear water conditions for both free-surface and pressure-flow conditions. Three-dimensional velocity measurements were taken at different positions along the centreline of the flume using an acoustic Doppler velocimeter. The results showed that the longitudinal and vertical velocity components of the pressure-flow increased in the vicinity of the pier as compared with those of the free-surface flow. Large values of the turbulence intensities, turbulent kinetic energy and Reynolds shear stress were observed at the upstream edge of the bridge deck within the shear layer and downstream of the pier under the deck due to the generation of wake vortices. Flow contraction and acceleration around the pier's sides resulted in a local increase of the bed shear stress.