The flow and turbulence structure at a rectangular bridge pier with a low angle of attack (original) (raw)

Detached Eddy Simulation (DES) is used to study the vortical structure of the flow around a high-aspect-ratio rectangular bridge pier with a small angle of attack. Though piers are generally de- signed to be closely aligned with the incoming flow at normal flow conditions, the angle of attack can in- crease significantly at flood conditions. This is particularly the case when a pier is situated near an abut- ment in a compound channel which is, in many cases, subject to varying flow orientations as the flow stage rises. Simulations are conducted with two angles of attack (0 0 and 15 0 ) at a channel Reynolds num- ber of 2.4× 10 5 . The paper focuses on the dynamics of the large-scale coherent structures forming around the bridge pier and their role in controlling the sediment entrainment and transport mechanisms at condi- tions corresponding to the start of the scour process (flat-bed channel). Simulation results show that for these conditions the horseshoe vortex system plays a rel...