Flow Structures Around Proposed Bridge Piers

The current study investigated the flow hydrodynamics around proposed bridge pier and made comparison with existing bridge pier. To quantify the flow structures around the piers, the flow and turbulence parameters are analysed to understand the interference of one bridge pier over another. The experiments were performed on recirculating channel of 15 m length, 0.89 m width and 0.65 m height. Instantaneous three-dimensional velocity data was recorded by acoustic Doppler velocimeter at different radial planes alpha = 0 degrees, 45 degrees, 90 degrees, 135 degrees and 180 degrees around the piers of both the bridges, where the distance (centre to centre) was maintained two times the diameter of pier (d = 8.8 cm). The flow structures, velocity fields, vector patterns, distributions of turbulence fields are analysed around the piers. The results of planned bridge pier are compared with existing one under identical flow in the clear waters. The results from the current study reveal that the flow velocity was decreased by 30% of the mean flow velocity at a = 180 degrees. Further, the turbulence was significantly reduced around the proposed bridge pier with respect to existing, due to sheltering effect imposed by the front pier. Turbulence intensities, turbulent kinetic energy and Reynolds shear stresses are decreased by 30%, 40% and 30%, respectively. Due to the horseshoe vortex, strength is reduced by 30% around new pier vis-a-vis the old one. The present study recommends that the placement of new bridge pier should be 2 to 3 times the diameter of the pier to avoid more scouring.