Evaluation Of Flow Behavior Around Bridge Piers

Abstract

- In the present study, the flow behavior around piers of different shapes is investigated at three different flow conditions of Froude numbers of 0.16, 0.32 and 0.64. Simulation analyses were performed using CFD techniques with the support of the ANSYS-CFX package. The obtained results have shown that the minimum eddy viscosity of 0.18 Pa s was noticed behind the cylindrical pier while the maximum value of about 0.49 Pa s was determined behind the triangular pier of downstream head. At a very low Reynolds number of 38, laminar flow, a pair of symmetric vortices are created just behind the cylindrical pier. Von Karman Vortices are created behind the piers under study at transient and turbulent flows. Regarding the drag force hitting the piers, the cylindrical shape was less subjected to drag force of water unlike the triangular pier of the downstream head, which shows the highest resistance. Due to the flow resistance, a pressure drop is created behind the piers. The cylindrical pier shows minimum drop of water level of about 0.46 m while the maximum value of about 0.64m in average was noticed behind the triangular piers. The cylindrical pier shows the best performance where the flowing water is less disturbed. The hexagon and square piers come in the second level where it is possible to use them instead of cylindrical piers if the architectural issue is urgent and here additional protection of the foundations is needed.